Efficient three-dimensional calibration method and system for cementum-enamel boundary

Abstract

The invention discloses a cementum-enamel boundary efficient three-dimensional calibration method and system, and relates to the technical field of digital oral medicine. Comprising the following steps: acquiring a three-dimensional surface model of a target tooth, sequentially selecting anatomical feature points from a tooth neck part of the model, determining three-dimensional space coordinates of the anatomical feature points, generating a sparse point set, and carrying out visualization processing on the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set. The discrete point set is converted into a continuous smooth curve, the continuous smooth curve is made to be attached to the surface of a tooth model, a final cementum-enamel boundary curve is obtained, and coordinates of the final cementum-enamel boundary curve are output and made to be highlighted and visualized in the three-dimensional surface model. According to the method, the efficiency can be greatly improved, the result precision is ensured, and the objectivity and repeatability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital dentistry, and in particular to a high-efficiency three-dimensional cement-enamel junction marking method and system. BACKGROUND

[0002] With the popularity of cone beam CT (CBCT) and intraoral scanning technology in the field of dentistry, three-dimensional digital diagnosis and treatment has become a trend. The CEJ is the anatomical demarcation line between the crown and the root, and is the golden benchmark for diagnosis, treatment planning and efficacy evaluation in periodontology, prosthodontics, orthodontics and other disciplines. For example, in periodontology, accurate quantification of key indicators such as root surface area, attachment loss degree, and bone resorption ratio all require accurate and accurate CEJ positioning as an absolute prerequisite. Therefore, developing a technology that can quickly, accurately, and repeatedly mark the CEJ on a three-dimensional dental model has great clinical significance and urgent market demand for improving the accuracy of digital dental diagnosis and treatment.

[0003] Therefore, to solve the problems existing in the prior art, a high-efficiency three-dimensional cement-enamel junction marking method and system are provided, which is a problem that needs to be solved by those skilled in the art. SUMMARY

[0004] Therefore, the present application provides a high-efficiency three-dimensional cement-enamel junction marking method and system, which can greatly improve efficiency, ensure result accuracy, and improve objectivity and repeatability.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A high-efficiency three-dimensional cement-enamel junction marking method, comprising the following steps:

[0007] Obtaining a three-dimensional surface model of a target tooth;

[0008] Selecting anatomical feature points in the cervical part of the model in sequence, determining the three-dimensional space coordinates of the anatomical feature points, and generating a sparse point set;

[0009] Visualizing the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set;

[0010] Converting the discrete point set into a continuous smooth curve and fitting it to the surface of the tooth model to obtain a final cement-enamel junction curve;

[0011] Outputting the coordinates of the final cement-enamel junction curve and highlighting it in the three-dimensional surface model.

[0012] Optionally, the anatomical points are set to 8, which are four main points and four axis angle points.

[0013] Optionally, obtaining the continuous smooth curve comprises: calculating a centroid according to the spatial positions of the 8 anatomical points, and sorting according to the azimuth angles of the anatomical points relative to the centroid, and generating a closed three-dimensional continuous smooth curve by using a cubic B-spline interpolation algorithm.

[0014] Optionally, obtaining the final cement-enamel junction curve comprises:

[0015] Traversing all surface vertices of the tooth model, a k-d tree index structure is established;

[0016] High-density sampling is performed on the three-dimensional continuous smooth curve to obtain sampling points, and the k-d tree index structure is used to find the vertex closest in spatial distance to the tooth surface and the sampling points;

[0017] All vertices are obtained, and an ordered point chain is constructed based on the vertices to finally generate the final cement-enamel junction curve.

[0018] Optionally, the closest in spatial distance is realized based on a nearest neighbor point search algorithm.

[0019] A cement-enamel junction efficient three-dimensional calibration system, which realizes any one of the cement-enamel junction efficient three-dimensional calibration methods described above, comprises a data acquisition module, a point calibration module, a visualization module, a data processing module, and a result output module connected in sequence.

[0020] The data acquisition module acquires a three-dimensional surface model of the target tooth.

[0021] The point calibration module sequentially selects anatomical feature points at the tooth neck of the model, determines the three-dimensional spatial coordinates of the anatomical feature points, and generates a sparse point set.

[0022] The visualization module visualizes the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set.

[0023] The data processing module converts the discrete point set into a continuous smooth curve, which is fitted to the surface of the tooth model to obtain a final cement-enamel junction curve.

[0024] The result output module outputs the coordinates of the final cement-enamel junction curve and visualizes it in the three-dimensional surface model.

[0025] Compared with the prior art, the application provides a high-efficiency three-dimensional calibration method and system for cement-enamel junction, and has the following beneficial effects: 1) the operation efficiency is improved by more than one order of magnitude under the premise of ensuring high-precision results, and high objectivity and repeatability of the calibration results are realized, and the operation is fast, accurate and consistent; 2) the complexity and time consumption of manual operation are greatly reduced, the technical threshold is reduced to the minimum, and ordinary doctors can easily operate; at the same time, the standardized point distribution rule also provides high-quality and consistent initial input for subsequent automatic processing; 3) the application ensures that the final output CEJ curve has absolute anatomical fidelity, and each point of the curve actually exists on the tooth surface. This ensures the accuracy and effectiveness of all downstream quantitative analysis (such as attachment area and tooth root length calculation) based on the curve, and the result is real and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute the embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0027] Figure 1 A high-efficiency three-dimensional calibration method for cement-enamel junction is disclosed in the application;

[0028] Figure 2a An interactive calibration horizontal plane window pane of CEJ feature points is disclosed in the application;

[0029] Figure 2b A coronal plane window pane of the interactive calibration of CEJ feature points is disclosed in the application;

[0030] Figure 2c A sagittal plane window pane of the interactive calibration of CEJ feature points is disclosed in the application;

[0031] Figure 2d A three-dimensional reconstruction window pane of the interactive calibration of CEJ feature points is disclosed in the application;

[0032] Figure 3 A three-dimensional model of teeth and a suspended CEJ feature point set is disclosed in the application;

[0033] Figure 4 A continuous smooth curve is disclosed in the application;

[0034] Figure 5 A final cement-enamel junction curve is disclosed in the application;

[0035] Figure 6 A high-efficiency three-dimensional calibration system block diagram of cement-enamel junction is disclosed. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0037] Referring to Figure 1 The present application discloses a high-efficiency three-dimensional calibration method of cement-enamel junction, comprising the following steps:

[0038] obtaining a three-dimensional surface model of a target tooth;

[0039] selecting anatomical feature points in the cervical part of the model in sequence, determining the three-dimensional space coordinates of the anatomical feature points, and generating a sparse point set;

[0040] visualizing the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set, as shown in Figure 3 ;

[0041] converting the discrete point set into a continuous smooth curve and making it fit to the surface of the tooth model to obtain a final cement-enamel junction CEJ curve;

[0042] outputting the coordinates of the final cement-enamel junction CEJ curve and making it highlighted and visible in the three-dimensional surface model.

[0043] Further, the three-dimensional surface model file of the target tooth is in the format of tooth_model.stl, and the model is composed of a large number of vertices and triangular facets.

[0044] Further, the anatomical points are set to 8, which are four main points and four axis angle points.

[0045] Specifically, the operator uses a mouse or other input device to click and place a predefined sparse point set composed of 8 anatomical feature points around the cervical part of the three-dimensional tooth model in sequence, and the selection of the 8 points has a clear anatomical guiding significance to ensure a comprehensive description of the CEJ morphology.

[0046] Further, referring to Figures 2a-2dAs shown, the four main sites are the central point of the mesial CEJ curve, the central point of the distal CEJ curve, the central point of the buccal (labial) CEJ curve, and the central point of the lingual (palatal) CEJ curve.

[0047] The four axial angle sites are the CEJ points at the four axial angle turning points of the mesial buccal (labial) side, the distal buccal (labial) side, the mesial lingual (palatal) side, and the distal lingual (palatal) side.

[0048] Further, after the operator completes the labeling of the 8 points, the software saves the three-dimensional spatial coordinates of the 8 points as a data file (for example, in.fcsv format) as input for subsequent automated processing. Usually completed within 30-60 seconds.

[0049] Further, with reference to Figure 4 As shown, obtaining a continuous smooth curve includes: calculating the centroid according to the spatial positions of the 8 anatomical points, and sorting according to the azimuth angles of the anatomical points relative to the centroid, and generating a closed three-dimensional continuous smooth curve using a cubic B-spline interpolation algorithm.

[0050] Specifically, the three-dimensional continuous smooth curve is a mathematically smooth ideal curve that roughly depicts the outline of the CEJ, but at this time it is still "floating" in space and does not have precise contact with the tooth surface 200.

[0051] Further, obtaining the final cement-enamel junction curve includes:

[0052] Traverse all surface vertices of the tooth model to establish a k-d tree index structure. Once the index is established, a millisecond-level fast query can be implemented for the nearest neighbor vertex of any spatial point to the tooth surface;

[0053] High-density sampling is performed on the three-dimensional continuous smooth curve to obtain sampling points, and the k-d tree index structure is used to find the vertices of the tooth surface that are closest in space to the sampling points;

[0054] All vertices are obtained, and an ordered point chain is constructed based on the vertices to finally generate the final cement-enamel junction curve, as shown in Figure 5 .

[0055] Specifically, the system performs high-density sampling (for example, collecting 300 equidistant points) along the initial spatial curve. For each point pi obtained by sampling, the system quickly and accurately finds the vertex vj closest in space to pi among all the vertices of the tooth model using the k-d tree index. The set of all found tooth surface vertices vj constitutes a new ordered point chain composed entirely of tooth surface vertices.

[0056] Further, the nearest in space is based on the nearest neighbor point finding algorithm.

[0057] Further, the system outputs the final CEJ curve (i.e. the sequence of projected vertex coordinates) in a standard data format for downstream applications (e.g. root area calculation). Meanwhile, the system displays this final curve on the tooth model in a highlighted color on the interactive interface for the operator to perform the final visual inspection and confirmation.

[0058] A highly efficient three-dimensional demarcation system for cement-enamel junction, which implements the highly efficient three-dimensional demarcation method for cement-enamel junction according to any one of the above, such as Figure 6 As shown, the system comprises a data acquisition module, a point demarcation module, a visualization module, a data processing module and a result output module connected in sequence.

[0059] The data acquisition module acquires a three-dimensional surface model of the target tooth.

[0060] The point demarcation module sequentially selects anatomical feature points at the tooth neck of the model, determines the three-dimensional space coordinates of the anatomical feature points, and generates a sparse point set.

[0061] The visualization module visually processes the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set.

[0062] The data processing module converts the discrete point set into a continuous smooth curve, which is fitted to the surface of the tooth model to obtain a final cement-enamel junction curve.

[0063] The result output module outputs the coordinates of the final cement-enamel junction curve and highlights the visualization of the curve in the three-dimensional surface model.

[0064] Using software such as Mimics and 3D Slicer, the three-dimensional surface models (.stl format) of the 10 teeth are segmented and extracted;

[0065] The above description enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for efficient three-dimensional calibration of the cement-enamel junction, characterized in that, The method comprises the following steps: obtaining a three-dimensional surface model of a target tooth; selecting anatomical feature points in sequence at the tooth neck of the model, determining the three-dimensional space coordinates of the anatomical feature points, and generating a sparse point set; visualizing the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set; converting the discrete point set into a continuous smooth curve and fitting it to the surface of the tooth model to obtain a final cement-enamel junction curve; outputting the coordinates of the final cement-enamel junction curve and highlighting the curve in the three-dimensional surface model.

2. The method according to claim 1, wherein the anatomical points are eight, including four main points and four axis angle points.

3. The method according to claim 2, wherein obtaining the continuous smooth curve comprises: calculating a centroid according to the spatial positions of the eight anatomical points, sorting the eight anatomical points according to the azimuth angles of the eight anatomical points relative to the centroid, and generating a closed three-dimensional continuous smooth curve by using a cubic B-spline interpolation algorithm.

4. The method according to claim 3, wherein obtaining the final cement-enamel junction curve comprises: traversing all surface vertices of the tooth model to establish a k-d tree index structure; high-density sampling the three-dimensional continuous smooth curve to obtain sampling points, and combining the k-d tree index structure to find the vertices closest in space to the sampling points on the surface of the tooth; obtaining all the vertices, constructing an ordered point chain based on the vertices, and finally generating the final cement-enamel junction curve.

5. The method according to claim 3, wherein the closest in space is realized based on a nearest neighbor searching algorithm. The method comprises the following steps: obtaining a three-dimensional surface model of a target tooth; selecting anatomical feature points in sequence at the tooth neck of the model, determining the three-dimensional space coordinates of the anatomical feature points, and generating a sparse point set; visualizing the three-dimensional surface model and the sparse point set in the same space to obtain a tooth model with a discrete point set; 6. A high efficient three-dimensional cement-enamel junction demarcation system for implementing the high efficient three-dimensional cement-enamel junction demarcation method according to any one of claims 1-5, characterized in that, converting the discrete point set into a continuous smooth curve and fitting it to the surface of the tooth model to obtain a final cement-enamel junction curve; outputting the coordinates of the final cement-enamel junction curve and highlighting the curve in the three-dimensional surface model. ​ ​ ​ ​

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