KR102138921B1 - Method for generating margin line of prep model in prosthesis design and prosthetic CAD apparatus therefor - Google Patents

Abstract

Disclosed are a method for generating a margin line of a prep model when designing a prosthesis and a prosthetic CAD apparatus performing the same. According to one embodiment, the method for generating the margin line of the prep model when designing the prosthesis comprises the steps of: acquiring each a pre-prep scan model and a post-prep scan model based on a prep work; classifying the post-prep scan model matched with the pre-prep scan model into an area to which the prep work has been applied (hereinafter referred to as a ′prep-applied area′) and an area to which the prep work is not applied (hereinafter referred to as an ′area not applied with prep′); and extracting a boundary line between the prep-applied area and the area not applied with the prep, and setting the boundary line as a margin line. According to the present invention, it is possible to automatically generate the margin line of the prep model.

Description

Method for generating margin line of prep model and prosthetic CAD device therefor when designing a prosthesis {Method for generating margin line of prep model in prosthesis design and prosthetic CAD apparatus therefor}

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 surgery refers to restoring a damaged tooth using a prosthesis. Prostheses include Crown, Inlay, Onlay, Coping, and Pontic. Before performing an actual prosthesis procedure, a virtual prosthesis suitable for a patient is designed through simulation, and the prosthesis is virtually combined with a target position. This is done through a computer aided design (CAD).

For the design of the prosthesis, a prep operation is required to remove the cavities or unnecessary parts of the original tooth. However, if the margin line is not created accurately in the prep model, if the final designed prosthesis is placed on the tooth, the edge of the deleted tooth that needs to be covered with the prosthesis is exposed, or the prosthesis does not need to be covered. A number of problems can occur, such as the prosthesis being made up to the part of the tooth that is not. Therefore, creating an accurate margin line on the prep model can be said to be the most important and basic task in the design of the prosthesis.

Korean Registered Patent 10-1810038 (announced on December 26, 2017)

According to one embodiment, a method for accurately and automatically generating a margin line of a preparation model during a prosthetic operation and a prosthetic CAD device for performing the same are proposed.

When designing a prosthesis according to an embodiment, a method for generating a margin line of a dental model includes pre-prep and post-prep scan models, respectively, based on the prep work, and pre-prep scan model matching with the pre-prep scan model. Extracting the boundary between the area to which this is applied (hereinafter referred to as the'prep application area') and the area to which the preparation is not applied (hereinafter, referred to as the'prep application area'), and the area between the application area and the non-prep area And setting it as a margin line.

The step of dividing the pre-applied area and the non-pre-applied area is a step in which each vertex is a center point for all vertices in a scan model after preparation, and a sphere having an arbitrary radius is set, and each vertex is set as a target. The vertex to which the prep was applied (hereinafter referred to as the'prep-applied vertex') and the vertex to which the prep was not applied, using the distance between the vertex of the pre-prep scan model and the distance between the nearest vertex (d). Hereinafter, the step of distinguishing the steps that do not apply to the preparations, and the triangles constituting the scan model after the preparation operation, the triangles that are not prepared according to whether the preparations of the three vertices constituting each triangle are applied (hereinafter, referred to as'triangles without preparation') It may include a step of dividing into a triangle (hereinafter referred to as a'prep application triangle').

The step of distinguishing the vertex with the prep applied and the non-prep applied vertex includes the step of classifying the vertex as a prep applied vertex if the vertex of the pre-prep scan model is not included in the set sphere, and the vertex of the pre-prep scan model contained in the sphere. , If the distance (d) to the nearest vertex among the included vertices is greater than an arbitrary threshold value, the vertex is classified as a prep application vertex, and the vertex of the pre-prep scan model is included in the sphere, and the included vertex If the distance (d) from the nearest vertex is smaller than an arbitrary threshold value, the corresponding vertex may include a step of dividing it into an unapplied vertex.

The step of dividing the pre-applied triangle and the pre-applied triangle is a pre-applied triangle when two or more vertices of the three vertices constituting each triangle are targets of the triangles constituting the scan model after the prep operation. It may include a step of dividing into a triangle, and a step that does not correspond to a pre-applied triangle into a pre-applied triangle.

The setting of the margin line may include extracting a boundary line of the preparation-applied triangles and setting the extracted boundary line as a margin line.

When designing a prosthesis, the method of generating a margin line of a dental model may further include generating a final margin line through correction of a margin line using smoothing.

Prosthetic CAD device according to another embodiment, the pre-prep and post-prep scan models, respectively, based on the prep operation, and the pre-prep scan model and the pre-prep scan model matched with the pre-prep application area and the pre-applied area And a margin line generating unit that extracts a boundary line between a preparation area divided by a prep area and a non-prep area and sets it as a margin line.

The preparation region division unit sets a sphere having an arbitrary radius with each vertex as a center point for all vertices of the scan model after preparation, and whether or not the vertices of the pre-prep scan model are included and included in the sphere set for each vertex. The distance between the closest vertex (d) is used to distinguish the prep-applied vertex and the non-prep vertex, and the triangles that make up the scan model after the prep work, depending on whether the prep is applied to the three vertices that make up each triangle. It can be divided into pre-applied triangle and pre-applied triangle.

The prep area division unit classifies the vertex as a prep application vertex if no vertex of the pre-prep scan model is included in the set sphere, includes the vertex of the pre-prep scan model in the sphere, and the vertex with the closest vertex. If the distance (d) is greater than an arbitrary threshold value, the vertex is classified as a prep application vertex, the vertex of the pre-prep scan model is included in the sphere, and the distance (d) to the nearest vertex among the included vertices is arbitrary. If it is less than the threshold value of, the corresponding vertex can be classified as a vertex without prep.

The preparatory region division unit divides the corresponding triangle into a preprep non-triangle, and when two or more vertices of the three vertices constituting each triangle target the triangles constituting the scan model after the prep operation, is a preprep non-applied triangle. A triangle that does not correspond to can be classified as a preparation applied triangle.

The margin line generating unit may extract a boundary line of the preparation-applied triangles and set the extracted boundary line as a margin line.

The prosthetic CAD device may further include a margin line correction unit that generates a final margin line through margin line correction using smoothing.

When designing a prosthesis according to an embodiment, if there is a tooth for manufacturing and applying a prosthesis by a method of generating a margin line of the dental model and a prosthetic CAD device performing the same, simply provide a scan model before and after preparation work as an input. The margin line can be automatically generated and provided in the prepared tooth model. With the scan model acquired through two scanning operations before and after preparation, an accurate margin line can be automatically generated without user manual intervention.

1 is a view showing the concept of a margin line,
2 is a view showing an example of the margin line generation by hand,
3 is a diagram showing an example of generating a margin line through one-click (One-Click),
Figure 4 is a view showing the configuration of a prosthetic CAD device according to an embodiment of the present invention,
5 is a view showing a detailed configuration of the control unit of FIG. 4 according to an embodiment of the present invention;
6 is a view showing a flow of a method for automatically generating a margin line according to an embodiment of the present invention,
7 is a view showing an example of an apex of a pre/post scan model (an example of a 2D cross section of a 3D scan model) according to an embodiment of the present invention;
8 is a view showing an example of drawing a sphere having a radius r at each vertex of a scan model after preparation according to an embodiment of the present invention;
FIG. 9 is a view showing an example of results in which all vertices of a pre-preparation scan model according to an embodiment of the present invention are divided into a prep application vertex and a non-prep vertex;
10 is a diagram showing an example of a prep application triangle and a prep unapplied triangle definition rule according to an embodiment of the present invention;
11 is a view showing an example of a scanning mesh model of a preparation tooth consisting of a preparation-applied triangle and a non-preparation triangle according to an embodiment of the present invention;
12 is a diagram showing an example of generating an initial margin line using a boundary of prep-applied triangles according to an embodiment of the present invention;
13 is a view showing an initial margin line generated by an initial margin line generating method according to an embodiment of the present invention,
14 is a view showing an example of applying a smoothing technique for initial margin line correction according to an embodiment of the present invention;
15 is a diagram illustrating a final margin line generated through initial margin line correction using a smoothing technique according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified 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 various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, 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 the description of the embodiments of the present invention, when it is determined that a detailed description of known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted, and terms to be described below are used in the embodiments of the present invention. The terms are defined in consideration of the function of. It can be changed according to the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

Combinations of each block in the accompanying block diagrams and steps in the flow charts may be performed by computer program instructions (execution engines), these computer program instructions being incorporated into a processor of a general purpose computer, special purpose computer, or other programmable data processing device. Since it can be mounted, the instructions executed through a processor of a computer or other programmable data processing device create a means to perform the functions described in each block of the block diagram or in each step of the flowchart.

These computer program instructions can also be stored in computer readable or computer readable memory that can be oriented to a computer or other programmable data processing device to implement a function in a particular way, so that computer readable or computer readable memory The instructions stored in it are also possible to produce an article of manufacture containing instructions means for performing the functions described in each block of the block diagram or in each step of the flowchart.

And since computer program instructions may be mounted on a computer or other programmable data processing device, a series of operation steps are performed on the computer or other programmable data processing device to create a process that is executed by the computer to generate a computer or other programmable It is also possible for 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 can represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical functions, and in some alternative embodiments referred to in blocks or steps It should be noted that it is possible for functions to occur out of sequence. For example, two blocks or steps shown in succession may in fact be executed substantially simultaneously, and it is also possible that the blocks or steps are performed in the reverse order of the corresponding function as necessary.

Hereinafter, 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 fully describe the present invention to those of ordinary skill in the art.

1 is a view showing the concept of the margin line.

Referring to FIG. 1, a margin line 116 is a term that defines an edge line where a prosthesis contacts a tooth when a prosthesis is placed on a tooth that requires prosthetic treatment. Prosthetics include Crown, Inlay, Onlay, Coping, and Pontic. In general, a prep operation is performed to perform prosthetic treatment, and the margin line 116 may be understood as a boundary line between the preparatory portion 112 and the preparatory portion 114. Prep work refers to the operation of removing the cavities or unnecessary parts of the original teeth in order to put the prosthesis over the teeth. In FIG. 1, a margin that is a boundary between the deleted tooth portion 112 and the unremoved tooth portion 114 in the model 110 after the preparation operation is performed by performing the preparation operation in the model 100 before the preparation operation. Line 116 is shown.

In the dental CAD program, if the prep model comes in as an input for prosthesis design, if the margin line 116 is not correctly created in the prep model, and the final designed prosthesis is placed on the tooth, the deleted tooth to be covered with the prosthesis A number of problems may occur, such as the prosthesis being made up to the part of the tooth that is not removed or need not be covered with the prosthesis. Therefore, it can be said that the operation of generating the correct margin line 116 on the preparation model is the most important and basic operation in the process of designing the prosthesis in the dental CAD program.

Hereinafter, a method of generating a margin line of a prep model in the process of designing a prosthesis through a dental CAD program will be introduced with reference to FIGS. 2 and 3.

2 is a view showing an example of generating a margin line by hand.

Referring to FIG. 2, while the user directly looks at the 3D form of the preparation model on the CAD program screen and checks the margin line 210, the margin line part 200 is clicked at regular intervals with a mouse or the like (Click) ) To manually generate the margin line 210.

FIG. 3 is a diagram illustrating an example of generating a margin line through one-click.

Referring to FIG. 3, when a user directly sees a 3D preparation model on a CAD program screen and clicks a point 300 included in the margin line 310 with a mouse or the like, the entire margin line 310 is automatically displayed. Can be created with An algorithm that generates a margin line 310 starting at the point of one click 300 and continuing with a large portion of curvature as one, using that the margin line is a larger part of the surface of the preparation model compared to other parts. Can be applied. Since the entire margin line area does not have to be clicked with a mouse, there is an advantage in that the working time is shortened compared to the manual operation described above with reference to FIG. 2.

Another method is to generate a margin line through an automated algorithm. With reference to FIG. 3, a step further from the above-described method of generating a margin line through one click is a method of automatically generating a margin line without interaction with a user or user input data. As in the method of generating a margin line through one click, draw the line with the largest curvature on the prep model as one (curvature analysis algorithm), or apply the method of automatically generating a margin line using artificial intelligence (AI). Can.

The margin line generation techniques described with reference to FIGS. 2 and 3 have the following two problems.

1. It takes a lot of effort and time from the user and the work is complicated. That is, the method of manually generating a margin line (see FIG. 2) has the advantage of generating an accurate margin line, but the user has to input the point corresponding to the margin line one by one by clicking with the mouse. There is a problem that it takes a lot of time and effort, and the work process is complicated and difficult.

2. Inaccurate results may differ from the actual margin line. The method of generating a margin line through one click (refer to FIG. 3) and the method of generating a margin line through an automated algorithm do not require a user to perform complicated tasks and do not take much time, but are applied to numerous prep models having different conditions and shapes. An inaccurate margin line may be output, and the user may correct it again, or a situation in which the margin line must be generated again using a method of manually generating a margin line (see FIG. 2 ).

The present invention is to solve the above-mentioned problems, and proposes a method capable of automatically generating an accurate margin line without user input and intervention. According to the present invention, there is no user intervention in the operation of generating the margin line itself, but 1. Pre-preparing two additional pre-preparing tasks of the pre-preparation and two pre-preparation two tooth models. . However, scanning is a basic task that must always be performed in the course of a general dental CAD program. The registration work has been developed with a variety of automatic registrations, that is, a technique that automatically aligns two scan models with the same coordinates and positions so that the same parts have the same coordinate values without user intervention. This is not a necessary part. Therefore, it can be said that the technology proposed in the present invention does not significantly affect the process of solving the problem.

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

Referring to FIG. 4, the prosthetic cad device 4 performs a cad process to assist in dental prosthesis in actual dentistry. The prosthetic CAD process refers to a series of processes for acquiring a patient's 3D tooth data, fetching a virtual prosthetic model from a library through computer program control, and placing the virtual prosthetic model in a target position. The 3D tooth data is data having 3D information of teeth including damaged target teeth. The target position is the target tooth position.

The prosthetic CAD device 4 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, smart phones, mobile phones, personal media players (PMPs), and personal digital assistants (PDAs). In addition to the prosthetic CAD program, the dental program includes a guide program, a scan program, and a medical image processing program. It can also be applied to other general medical programs in addition to dental prosthetic surgery.

Hereinafter, the configuration of the prosthetic CAD device 4 having the above-described features will be described later with reference to FIG. 4.

Referring to FIG. 4, the prosthetic CAD device 4 according to an embodiment includes a data acquisition unit 40, a storage unit 42, a control unit 44, an input unit 46, and an output unit 48.

The data acquisition unit 40 acquires image data from a patient. Image data required for prosthetic surgery include scan model data. The data acquisition unit 40 may execute the scan model data in a program or load it from a web page and a server. The scan model data is data with information of real teeth, including damaged teeth. The scan model data can be obtained by scanning a plaster model created by modeling a patient's mouth with a 3D scanner. As another example, it may be obtained by scanning the inside of a patient's mouth using a 3D intra-oral scanner. The obtained scan model data may be stored in the storage unit 42.

The data acquisition unit 40 according to an embodiment includes a pre-preparation scan model acquiring unit 400 for acquiring a pre-preparation scan model based on a prep operation, and a post-prep scan model acquiring unit 402 for acquiring a pre-preparation scan model ).

The storage unit 42 stores various data such as information required for performing the operation of the prosthetic CAD device 4 and information generated according to the operation. In the storage unit 42 according to an embodiment, model data of individual patients is stored, and model data of a specific patient among all model data may be provided to the control unit 44 according to a user's request during dental treatment simulation. In addition, the storage unit 42 may have a prosthetic library composed of a plurality of prosthetic model data and provide it to the control unit 44.

The control unit 44 controls each component while establishing a prosthetic surgical plan through control by a computer program. The control unit 44 manages screen information displayed on the screen through the output unit 48 and performs a simulation of combining a virtual prosthesis object with a medical image. The medical image combined with the virtual object refers to a multidimensional image of a 2D, 3D, etc. in which a patient's tooth arrangement is generated for prosthetic surgery planning. Various types of images, such as X-ray, CT, panoramic images, oral scan images, images generated through reconstruction, and images matching multiple images, can be used in the prosthetic surgery plan.

The control unit 44 according to an embodiment accurately and automatically generates a margin line of the preparation model during prosthetic work. The detailed configuration of the control unit 44 will be described later with reference to FIG. 5.

The output unit 48 displays the image data on the screen. At this time, the output unit 48 may display the margin line of the preparation model generated through the control unit 44 on the screen. The input unit 46 receives various commands including user manipulation signals.

5 is a diagram illustrating a detailed configuration of the control unit of FIG. 4 according to an embodiment of the present invention.

Referring to FIG. 5, the control unit 44 includes a model matching unit 440, a preparation region division unit 442, a margin line generation unit 444, and a margin line correction unit 446.

The model matching unit 440 matches the pre-preparation scan model and the pre-preparation scan model. Note that in order to perform the matching operation, there must be a common portion where the pre-preparation scan model and the pre-preparation scan model overlap sufficiently.

The preparation region division unit 442 is an area to which a preparation operation is applied to a pre-preparation scan model and a pre-preparation scan model (hereinafter referred to as a'prep application area') and an area to which no prep operation is applied (hereinafter,'prep is not applied') Area).

The preparation area division unit 442 according to an embodiment sets a sphere having an arbitrary radius with each vertex as a center point for all vertices of a scan model after preparation. In addition, the vertex to which the preparation was applied using the vertex of the pre-preparation scan model and the distance (d) to the nearest vertex among the included vertices (hereinafter referred to as'prep application vertex') and The vertex to which the preparation is not applied (hereinafter, a vertex not applied to the preparation) is distinguished. For example, if none of the vertices of the pre-preparation scan model are included in the set sphere, the vertex is classified as a prep application vertex. If the vertex of the pre-prep scan model is included in the sphere, and the distance (d) to the nearest vertex among the included vertices is greater than an arbitrary threshold value, the vertex is classified as a vertex to be applied. On the other hand, if the vertex of the pre-prep scan model is included in the sphere, and the distance (d) to the nearest vertex among the included vertices is less than an arbitrary threshold value, the vertex is classified as a vertex without prep.

Subsequently, the preparation region division unit 442 refers to triangles constituting the scan model after preparation, and triangles that are not prepared according to whether three vertices constituting each triangle are applied (hereinafter, referred to as'non-prepared triangle'). ) And prepared triangles (hereinafter referred to as the prepared triangles). For example, when two or more vertices among the three vertices constituting each triangle are targets of the triangles constituting the scan model after the preparation operation, the corresponding triangle is classified as a non-prepared triangle. In contrast, a triangle that does not correspond to a pre-applied triangle is classified as a pre-applied triangle.

The margin line generating unit 444 extracts a boundary line between the preparation application area and the non-preparation area and sets it as a margin line. For example, the margin line generation unit 444 may extract the boundary lines of the preparation triangles divided through the preparation area division unit 442 and set the extracted boundary line as a margin line.

The margin line correction unit 446 generates a final margin line through margin line correction using smoothing. Smoothing is a technique for smoothing the obtained image. The average number of counts of each point on the obtained margin line is averaged. There is a smoothing method that takes a simple average when averaging, and a smoothing method that averages each point.

6 is a flowchart illustrating a method for automatically generating a margin line according to an embodiment of the present invention.

Referring to FIG. 6, a method of automatically generating a margin line in a prepared tooth model through comparison and analysis of a pre/post scan model consists of 7 steps. Using the proposed method, if there is a tooth for manufacturing and applying a prosthesis, if a tooth model before and after preparation is scanned and provided as an input, a margin line is automatically generated and output from the prepared tooth model.

1. Pre-preparation scan model acquisition step (S610)

The prosthetic CAD device acquires a preprep scan model 681 that scans a tooth prior to preparation.

2. Post-preparation scan model acquisition step (S620)

Subsequently, the prosthetic CAD device acquires a scan model 682 after the preparation that scans the teeth after preparation. At this step (S620), the part to be noted is that a matching operation must be performed in the following process, so that a common portion where the pre-preparation scan model 681 and the pre-preparation scan model 682 sufficiently overlap exists (S615). to be.

When the preparation is performed, the shape of the teeth is completely different, so a scanning operation must be performed so that the surrounding area where the preparation is performed is sufficiently included, so that accurate alignment results can be obtained in the next process.

3. Matching step of pre/post scan model (S630).

Subsequently, the prosthetic CAD device matches the two scan models 681 and 682 before and after preparation work coming into the input. Since the prepared area has a completely different shape, the matching operation should be performed using the surrounding area to which the preparation operation is applied. Matching operations include 3-point matching (matching method that requires the user to enter 3 correspondence points), 1-point matching (matching method that the user must enter one correspondence point), and automatic matching (two scans without user input) The method of matching the model) may be selectively applied, and when automatic matching is used, this process may be omitted.

4. Preparatory application area and non-preparation area classification step (S640)

The prosthetic CAD device, when two scan models (681, 682) before and after preparation are correctly matched, all vertices of the scan model (682) after preparation are applied to the area where the preparation operation is applied (hereinafter referred to as'prep'). It is divided into'area') (683-1) and an area to which prep work is not applied (hereinafter referred to as'area without prep') (683-2). An embodiment of the classification operation will be described later with reference to FIGS. 7 to 9.

5. Step of extracting the boundary line between the area where the preparation is applied and the area where the preparation is not applied (S650)

The prosthetic CAD device extracts the boundary line 684 between the pre-applied area and the pre-applied area after passing through the pre-applied area and pre-applied area division step S640. An embodiment of the boundary line extraction step S650 will be described later with reference to FIGS. 10 to 13.

6. Boundary line correction step (S660)

The boundary line 684 generated after the boundary line extraction step (S650) becomes an initial margin line 685, and the initial margin line 685 has a rough line and includes errors when compared to an actual margin line. Therefore, by applying a smoothing technique to the 3D Line (Curve), the line is smoothed to compensate for the final margin line 686 that can be actually used. An embodiment of the boundary correction step S660 will be described later with reference to FIGS. 14 and 15.

7. Final margin line output step (S670)

The prosthetic CAD device outputs a final margin line that is a result of smoothing applied.

7 is a view showing an example of a vertex of a pre/post scan model (an example of a 2D cross section of a 3D scan model) according to an embodiment of the present invention, and FIG. 8 is after preparation according to an embodiment of the present invention FIG. 9 is a diagram illustrating an example of drawing a sphere having a radius r at each vertex of the scan model, and FIG. 9 is divided into a vertex applied to a prep and a non-prep applied vertex after the preparation according to an embodiment of the present invention. It is a diagram showing an example of the result.

Referring to FIGS. 7 to 9, a task of classifying a scan model after preparation into a prep application area and a non-prep area may be performed according to the following process.

The scan model may be composed of triangular mesh data, and each point of the mesh data is called a vertex. As shown in FIG. 7, the vertices for the pre-preparation scan model include the vertices 710 of the pre-preparation scan model, the vertex 720 of the pre-preparation scan model, and the vertex post-prep scan model of the pre-preparation scan model. The vertices are divided into overlapping vertices 730.

For all vertices of the post-prep scan model defined with reference to FIG. 7, each vertex V of the post-prep scan model is a central point, and a sphere having an arbitrary radius r (sufficiently small value) as shown in FIG. Set (sphere). At this time, if none of the vertices of the pre-prep scan model is included in the set sphere, the corresponding vertex V 720 is defined as a vertex to which a preparation is applied (hereinafter referred to as a'prep-applied vertex'). If the sphere contains the vertex of the pre-prep scan model and the distance (d) from the nearest vertex is greater than an arbitrary threshold, the corresponding vertex V is defined as the vertex to which the prep is applied. do. If the vertex of the pre-prep scan model is included in the sphere, and the distance between the nearest vertex (d) is less than an arbitrary threshold, the corresponding vertex V(730) is the vertex to which the prep is not applied ( Hereinafter, it is defined as a peak not applied to preparation. Any threshold value is a sufficiently small reference distance value. 8, all vertices of the pre-preparation scan model are divided into a prep application vertex 910 and a non-prep vertex 920 as illustrated in FIG. 9.

10 is a diagram illustrating an example of a rule for defining a preparation applied triangle and a triangle not applying a preparation according to an embodiment of the present invention.

Referring to FIGS. 6 and 10, the triangles constituting the scan model 682 after the preparation operation after the preparation applied vertex and the area not applied to preparation are determined according to whether the preparation of the three vertices constituting the triangle is applied to FIG. 10. It is divided into four cases as shown. At this time, when two or more vertices are not applied to a prep, the corresponding triangle is defined as a non-prepped triangle (hereinafter referred to as a'prepped non-prepared triangle'), and a triangle that does not correspond to a pre-applied triangle is a prepped triangle ( Hereinafter, it is referred to as'preparation triangle'.

11 is a view showing an example of a scanning mesh model of a preparation tooth consisting of a preparation-applied triangle and a non-preparation triangle according to an embodiment of the present invention, and FIG. 12 is a view of preparation-applied triangles according to an embodiment of the present invention A diagram showing an example of generating an initial margin line using a boundary, and FIG. 13 is a diagram showing an initial margin line generated by the method of generating an initial margin line according to an embodiment of the present invention.

If the scan model after preparation is divided into a pre-applied triangle and no pre-applied triangle, results as shown in FIG. 11 can be obtained. Here, by extracting the boundary of the pre-applied triangles, results as shown in FIGS. 12 and 13 can be obtained. The extracted boundary line becomes the initial margin line 1200. Note that the initial margin line 1200 may be different from the actual margin line 1100.

14 is a view showing an example of applying a smoothing technique for initial margin line correction according to an embodiment of the present invention, and FIG. 15 is through an initial margin line correction applying a smoothing technique according to an embodiment of the present invention This is a diagram showing the generated final margin line.

14 and 15, the initial margin line 1200 is corrected to a final margin line 1500 that can be actually used as the smoothing process 1400 is performed.

So far, the present invention has been focused on the embodiments. Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be interpreted as being included in the present invention.

Claims (12)

Obtaining pre-prep and post-prep scan models respectively based on prep work;
Triangles consisting of vertices and three vertices for the pre-pre-scan scan model matched with the pre-prep scan model are referred to as the area where the prep operation is applied (hereinafter referred to as the'prep application area') and the area where no prep operation is applied. (Hereinafter referred to as'prep unapplied area'); And
Extracting a boundary line between the pre-applied area and the non-prep area and setting it as a margin line;
Method for generating a margin line of a dental model when designing a prosthesis comprising a. The method of claim 1, wherein the step of dividing the area into which the preparation is applied and the area where the preparation is not applied is performed.
Setting a sphere having an arbitrary radius with each vertex as a center point for all vertices of the scan model after preparation;
The vertex to which the prep was applied (hereinafter referred to as'prep application vertex') and the prep using the vertex of the pre-prep scan model in the sphere set for each vertex and the distance (d) from the nearest vertex. The step of distinguishing the unapplied vertex (hereinafter, not applied to the vertex); And
The triangles constituting the scan model after the preparation operation, the triangles that are not prepared according to whether three vertices of each triangle are applied (hereinafter referred to as a'non-prepared triangle') and the triangles that are prepared (hereinafter, prepared) The application triangle');
Method for generating a margin line of a dental model when designing a prosthesis comprising a. The method of claim 2, wherein the step of distinguishing the pre-applied vertex and the non-prepared vertex is
If a vertex of a preprep scan model is not included in the set sphere, the corresponding vertex is divided into a prep application vertex;
If the vertex of the pre-prep scan model is included in the sphere, and the distance (d) to the nearest vertex among the included vertices is greater than an arbitrary threshold value, the corresponding vertex is divided into a vertex to be applied; And
If the vertex of the pre-prep scan model is included in the sphere, and the distance (d) to the nearest vertex among the included vertices is less than an arbitrary threshold value, the corresponding vertex is classified as a vertex without prep;
Method for generating a margin line of a dental model when designing a prosthesis comprising a. According to claim 2, The step of dividing the pre-applied triangle and pre-applied triangle is
If two or more vertices of the three vertices constituting each triangle are targeted to the triangles constituting the scan model after the preparation, when the two or more vertices are the unprepped vertices, dividing the triangle into a non-prepared triangle; And
Dividing a triangle that does not correspond to a pre-applied triangle into a pre-applied triangle;
Method for generating a margin line of a dental model when designing a prosthesis comprising a. The method of claim 2, wherein setting the margin line is
Extracting a boundary line of the preparation-applied triangles; And
Setting the extracted boundary line as a margin line;
Method for generating a margin line of a dental model when designing a prosthesis comprising a. The method of claim 1, wherein in the design of the prosthesis, the method of generating a margin line of the tooth model
Generating a final margin line by correcting the margin line using smoothing;
A method of generating a margin line of a dental model when designing a prosthesis, further comprising a. A data acquiring unit for acquiring pre-prep and post-prep scan models, respectively, based on the prep work;
A prep region division unit for dividing triangles composed of vertices and three vertices into a prep application region and a non-prep region for a preprep scan model matched with a preprep scan model; And
A margin line generating unit that extracts a boundary line between a pre-applied area and a non-pre-applied area and sets it as a margin line;
Prosthetic CAD device comprising a. The preparation region division unit of claim 7
After preparation, for all vertices in the scan model, each vertex is the center point, and a sphere with an arbitrary radius is set.
Pre-prep vertices and non-prep vertices are distinguished by using the vertex of the pre-prep scan model and the distance from the nearest vertex (d) in the sphere set for each vertex.
A prosthetic CAD device characterized in that the triangles constituting the scan model after the preparation work are divided into a non-prepared triangle and a prep applied triangle according to whether three vertices constituting each triangle are applied. According to claim 8, The preparation region division
If none of the vertices of the pre-prep scan model are included in the set sphere, the vertex is classified as a prep application vertex,
If the vertex of the pre-prep scan model is included in the sphere, and the distance between the nearest vertex (d) is greater than an arbitrary threshold, the vertex is classified as a vertex applied to the prep,
Prosthetic CAD device characterized in that the vertex of the pre-preparation scan model is included in the sphere and the distance (d) from the nearest vertex is less than an arbitrary threshold value, and the vertex is classified as an unapplied vertex. . According to claim 8, The preparation region division
If two or more vertices of the three vertices constituting each triangle are targets of the triangles constituting the scan model after preparation, the corresponding triangle is classified as a non-prep triangle,
Prosthetic CAD device characterized in that the triangular that does not correspond to the pre-applied triangle is divided into a pre-applied triangle. The method of claim 8, wherein the margin line generation unit
Prosthetic CAD device, characterized in that to extract the boundary of the pre-applied triangles, and set the extracted boundary line as a margin line. The prosthetic CAD device of claim 7,
A margin line correction unit that generates a final margin line by correcting the margin line using smoothing;
Prosthetic CAD device further comprising a.

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