A method for measuring the thickness of the enamel of any point on the surface of the upper front teeth

Abstract

The application discloses a kind of upper front teeth dental surface arbitrary point's dental enamel thickness measurement method, comprising the following steps: obtaining target upper front teeth CBCT image;Select the dental surface type point of upper front teeth, obtain each type point coordinate;According to type point coordinate, NURBS surface control point is solved, and NURBS surface is generated by control point;NURBS surface is discretized, and the thickness information of dental enamel arbitrary point is generated.The upper front teeth dental enamel thickness is automatically generated, and the efficiency of dental enamel thickness measurement is greatly improved.The method is non-invasive to teeth, and has smaller controllable error.The algorithm can help to more deeply study the mechanical and optical properties of teeth in combination with the microstructure of teeth, and provides convenience for studying the internal structure of upper front teeth, multi-scale modeling of teeth and optical or mechanical analysis.

Description

Technical Field

[0001] This invention relates to the field of oral medicine, specifically to a method for measuring the enamel thickness at any point on the surface of the maxillary anterior teeth. Background Technology

[0002] Existing methods for measuring the enamel thickness of the upper anterior teeth mainly include:

[0003] (1) Tooth section measurement method: The tooth section measurement method involves cutting the extracted maxillary anterior teeth with a slow-speed cutting machine to prepare a section of the maxillary anterior teeth, and measuring the thickness of the enamel on the section using a stereomicroscope. The measurement accuracy is relatively high, but it requires destructive treatment of the teeth, making it unusable in actual clinical work, and this measurement method relies on manual labor.

[0004] (2) Plaster model measurement method: The plaster model measurement method involves taking an impression of the patient's teeth and casting a plaster model, then measuring the enamel thickness of the upper anterior teeth using calipers. Compared to the tooth slice measurement method, it does not require invasive procedures on the teeth. However, since the cast plaster model only records the surface information of the teeth, it can only measure the enamel thickness at the incisal edge; and there are errors in taking the impression and casting the model, which reduces the accuracy of the measurement.

[0005] (3) CBCT Measurement Method: The CBCT measurement method obtains cross-sectional images of the patient's upper anterior teeth by taking CBCT scans. Built-in software is used to measure the distance between points on the enamel surface and points on the dentin surface, thus obtaining enamel thickness information. Compared to tooth slice measurement, it does not require invasive procedures on the teeth; compared to plaster model measurement, software measurement is relatively convenient. However, distance measurement still relies on manual labor, which is time-consuming and labor-intensive, and errors are inevitable due to the limited visual acuity of the human eye. If sufficient thickness information from multiple points on the enamel is required, the workload is enormous.

[0006] Therefore, how to quickly obtain thickness information from a sufficient number of points on the enamel and ensure its measurement accuracy is a problem that urgently needs to be solved in the field of oral medicine. Summary of the Invention

[0007] This invention provides a method for measuring enamel thickness at any point on the surface of the upper anterior teeth, which greatly improves the efficiency of enamel thickness measurement while ensuring accuracy. The method includes the following steps:

[0008] Step 1: Acquire CBCT images of the target upper anterior teeth;

[0009] Step 2: Establish a three-dimensional coordinate system, select the tooth surface value points of the upper anterior teeth, and obtain the coordinates of each value point;

[0010] Step 3: Obtain the control points of the NURBS surface based on the coordinates of the model value points, and generate the NURBS surface using the control points;

[0011] Step 4: Discretize the NURBS surface to generate thickness information for any point on the enamel.

[0012] Based on the above scheme, further, in step two, the enamel surface of the upper anterior teeth is divided into the labial enamel surface and the lingual enamel surface, and the dentin surface of the upper anterior teeth is divided into the labial dentin surface and the lingual dentin surface; multiple feature points are selected on each surface as the shape value points of the surface, and the three-dimensional coordinates of the shape value points are output.

[0013] Based on the above scheme, in step two, 20 feature points are selected on each surface as the shape value points of the surface.

[0014] Based on the above scheme, further, in step two, the selection method for the shape value points of each surface is as follows: establish a reference plane corresponding to the surface, generate a first plane orthogonal to the reference plane through the most convex point on the surface, generate a second plane orthogonal to the reference plane through the intersection point of the surface and the outermost edge of the reference plane, and the first plane and the second plane are parallel; select one or more planes between the first plane and the second plane, namely the third plane...the Nth plane, the two endpoints of the intersection line between each plane and the corresponding surface are the shape value points, and the one or more points with the smallest curvature on each intersection line are the shape value points.

[0015] Based on the above scheme, further, in step two, the selection method for the shape value points of each surface is as follows: For the labial surface of enamel, a plane passing through the long axis of the tooth and parallel to the incisal edge is established as a reference plane. A plane orthogonal to the reference plane is generated through the most convex point of the labial surface of enamel, denoted as f1; a plane orthogonal to the reference plane is generated through the incisal edge, denoted as f4; f1 is translated 2mm to f4 to generate f2, and f4 is translated 2mm to f1 to generate f3; the intersection line of f1-f4 with the labial surface of enamel is denoted as c1-c4; the two endpoints and three points with minimum curvature on c1-c4 are respectively taken as the shape value points of the labial surface of enamel, for a total of 20 points; the shape value points on the labial surface of dentin, the lingual surface of dentin, and the lingual surface of enamel are selected in the same way.

[0016] Based on the above scheme, further, in step three, the control points of the NURBS surface are obtained by inverse control point algorithm, and the labial NURBS surface of enamel, the labial NURBS surface of dentin, the lingual NURBS surface of dentin, and the lingual NURBS surface of enamel are generated respectively.

[0017] Building upon the above scheme, further, in step four, the four surfaces are discretized into point clouds using the NURBS surface equations. The accuracy of this algorithm is primarily determined by the number of discrete points, which can be adjusted according to specific requirements. For any point on a given NURBS surface, the enamel thickness corresponding to that point is determined based on the relationship between its minimum distances to the other three NURBS surfaces.

[0018] Based on the above scheme, in step four, the four surfaces are discretized into 10,000 discrete point clouds respectively using the NURBS surface equation.

[0019] Based on the above scheme, further, in step four, for any point on the NURBS surface of the labial or lingual surface of enamel, if the minimum distance between that point and the two NURBS surfaces of the labial and lingual surfaces of dentin are not equal, then the minimum of the two values ​​is the corresponding enamel thickness at that point.

[0020] Based on the above scheme, further, in step four, for any point on the NURBS surface of the labial or lingual enamel surface, if the minimum distance between that point and the two NURBS surfaces of the labial and lingual dentin surfaces is equal, then a straight line orthogonal to the reference plane corresponding to the NURBS surface where that point is located is drawn through that point. The distance between the intersection of the straight line and the other NURBS surface of the enamel surface and that point is the enamel thickness corresponding to that point.

[0021] Each NURBS surface does not participate in the distance determination; instead, the point cloud after discretization participates in the determination.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] This invention provides a method for measuring enamel thickness at any point on the surface of the maxillary anterior teeth. The method automatically generates the enamel thickness of the maxillary anterior teeth, significantly improving the efficiency of enamel thickness measurement. This method is non-invasive and has a small, controllable error. The algorithm, combined with the microstructure of teeth, helps to study the mechanical and optical properties of teeth in greater depth, facilitating the study of the internal structure of the maxillary anterior teeth, multi-scale modeling of teeth, and optical or mechanical analysis. It overcomes the shortcomings of existing technologies, such as heavy reliance on manual measurement of maxillary anterior tooth enamel thickness, invasiveness, and large errors. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0025] Figure 1 This is a logic flowchart for an embodiment;

[0026] Figure 2 This is a schematic diagram of CBCT in the embodiment;

[0027] Figure 3 This is a schematic diagram of the reference plane and orthogonal plane of the labial surface of tooth enamel in the embodiment.

[0028] Figure 4 This is a schematic diagram of the intersection line between the orthogonal plane and the labial surface of the enamel in the embodiment;

[0029] Figure 5 This is a schematic diagram showing the selection of shape value points on the intersection line in the embodiment;

[0030] Figure 6 This is a schematic diagram of the NURBS surface control points in the embodiment;

[0031] Figure 7 This is a schematic diagram of the NURBS surface of the labial surface of tooth enamel in the embodiment;

[0032] Figure 8 This is a schematic diagram of the discretized point cloud of the NURBS surface of the labial surface of tooth enamel in the embodiment;

[0033] Figure 9 This is a schematic diagram showing the positional relationship of the four tooth surface surfaces generated in the embodiment.

[0034] Figure 10 This is a schematic diagram showing the positional relationship of the four tooth surfaces in the embodiment.

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0037] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0038] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0039] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0040] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0041] Those skilled in the art will understand that all or part of the steps in the above facts and methods can be implemented by a program instructing related hardware. The program or the program described therein can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: at this time, the corresponding method steps are introduced. The storage medium can be ROM / RAM, magnetic disk, optical disk, etc.

[0042] Example:

[0043] like Figure 1 As shown in this embodiment, a method for measuring the enamel thickness at any point on the surface of the upper anterior teeth, which measures the enamel thickness at a point on the labial surface of the enamel, includes the following steps:

[0044] Step 1: As Figure 2 As shown, CBCT images of the target's upper anterior teeth were captured;

[0045] Step 2: Establish a three-dimensional coordinate system, select the tooth surface value points of the upper anterior teeth, and obtain the coordinates of each value point;

[0046] Preferred, such as Figure 10 As shown, the enamel surface of the upper anterior teeth is divided into the labial enamel surface (denoted as F1) and the lingual enamel surface (denoted as F4), and the dentin surface of the upper anterior teeth is divided into the labial dentin surface (denoted as F2) and the lingual dentin surface (denoted as F3). Twenty feature points are selected on each surface as the shape value points of the surface, and the three-dimensional coordinates of the shape value points are output.

[0047] The selection method for the shape value points of each surface is as follows: Establish a reference plane corresponding to the surface, generate a first plane orthogonal to the reference plane through the most convex point on the surface, generate a second plane orthogonal to the reference plane through the intersection point of the surface and the outermost edge of the reference plane, and the first plane and the second plane are parallel; select one or more planes between the first plane and the second plane, namely the third plane...the Nth plane, the two endpoints of the intersection line between each plane and the corresponding surface are the shape value points, and the one or more points with the smallest curvature on each intersection line are the shape value points.

[0048] Preferred, such as Figure 3 As shown, for the labial surface of enamel F1, a plane passing through the long axis of the tooth and parallel to the incisal edge is established as a reference plane. A plane orthogonal to the reference plane is generated through the most convex point of the labial surface of enamel F1, denoted as f1; a plane orthogonal to the reference plane is generated through the incisal edge, denoted as f4; f1 is translated 2mm towards f4 to generate f2, and f4 is translated 2mm towards f1 to generate f3; as shown... Figure 4 As shown, the intersection of f1-f4 and the labial surface of tooth enamel F1 is denoted as c1-c4; Figure 5 As shown, the two endpoints of c1-c4 and the three points with the minimum curvature are taken as the model value points of the labial surface of enamel F1, for a total of 20 points; the model value points on the labial surface of dentin F2, the lingual surface of dentin F3 and the lingual surface of enamel F4 are selected in the same way.

[0049] Step 3: Obtain the control points of the NURBS surface based on the coordinates of the model value points, and generate the NURBS surface using the control points;

[0050] Preferred, such as Figure 6As shown, the NURBS surface control points are obtained by inverse control point algorithm. Based on 20 shape points on c1-c4, 28 curve control points are obtained, as shown below. Figure 7 As shown, a NURBS surface for the labial surface of enamel (denoted as S1) is generated. Similarly, a NURBS surface for the labial surface of dentin (denoted as S2), a NURBS surface for the lingual surface of dentin (denoted as S3), and a NURBS surface for the lingual surface of enamel (denoted as S4) are calculated and generated. The positional relationships between S1, S2, S3, and S4 are as follows. Figure 9 As shown.

[0051] Step 4: Discretize the NURBS surface to generate thickness information for any point on the enamel.

[0052] The accuracy of this algorithm is mainly determined by the number of discrete points, which can be adjusted according to specific needs. For any point on a NURBS surface, the enamel thickness corresponding to that point is determined based on the relationship between its minimum distances to the other three NURBS surfaces.

[0053] Preferred, such as Figure 8 As shown, the NURBS surface S1 of the labial surface of enamel is discretized into a discrete point cloud of 10,000 using the NURBS surface equation. The discrete point clouds of the labial surface of dentin S2, the lingual surface of dentin S3, and the lingual surface of enamel S4 are generated in the same way.

[0054] For any point on the labial enamel NURBS surface S1 (F4NURBS surface) or the lingual enamel NURBS surface S4, if the minimum distance between this point and the two NURBS surfaces S2 and S3 (labial and lingual enamel surfaces) is not equal, then the minimum of the two distances is the corresponding enamel thickness at that point. For any point on the labial enamel NURBS surface S1 (F4NURBS surface) or the lingual enamel NURBS surface S4, if the minimum distance between this point and the two NURBS surfaces S2 and S3 (labial and lingual enamel surfaces) is equal, then a straight line orthogonal to the reference plane corresponding to the NURBS surface at that point is drawn through this point. The distance between the intersection of this straight line and another enamel NURBS surface (lingual enamel NURBS surface S4 or labial enamel NURBS surface S1) and this point is the corresponding enamel thickness at that point.

[0055] Preferably, for any point P on the labial enamel NURBS surface S1 (F4), traverse 10000 discrete points on the labial dentin NURBS surface S2 and the lingual dentin NURBS surface S3 to obtain the points P2 and P3 on the labial dentin NURBS surface S2 and the lingual dentin NURBS surface S3 with the minimum distance from P. When the distance L1 between P and P2 is not equal to the distance L2 between P and P3, output the distance L1 as the enamel thickness at point P. When the distances L1 and L2 are equal, draw a straight line orthogonal to the reference plane through P, and record the intersection of this line and the lingual enamel NURBS surface S4 as P4. Output the distance L3 between P and P4 as the enamel thickness at point P.

[0056] L1 refers to the shortest distance from a point on the labial surface of the enamel to the labial surface of the dentin, and is the definition of enamel thickness in dentistry. A meaningful perspective for observing enamel thickness is parallel to a reference plane. The equality of L1 and L2 refers to the situation at the incisal edge of anterior teeth, where there is no dentin, only enamel. In this case, the enamel thickness at a point on the labial surface of the enamel should be calculated by drawing a ray parallel to the line of sight through that point. The distance between the intersection of this ray and the lingual surface of the enamel and the aforementioned point on the labial surface of the enamel is the enamel thickness, also known as L3.

[0057] In this application, surfaces S1-S4 do not participate in the determination of distances L1, L2, and L3; instead, the point cloud after discretization of S1-S4 participates in the determination. This embodiment automatically generates the enamel thickness of the upper anterior teeth, greatly improving the efficiency of enamel thickness measurement. This method is non-invasive to teeth and has a small, controllable error. This algorithm, combined with the microstructure of teeth, can help to study the mechanical and optical properties of teeth more deeply, providing convenience for studying the internal structure of the upper anterior teeth, multi-scale modeling of teeth, and optical or mechanical analysis. It overcomes the shortcomings of the aforementioned prior art, which relies heavily on manual measurement of upper anterior tooth enamel thickness, is invasive to teeth, and has a large error.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of measuring the thickness of the enamel of any point of the dental surface of the upper front teeth, characterized by, The method comprises the following steps: Step one: obtaining CBCT image of target upper anterior teeth; Step two: establishing three-dimensional coordinate system, selecting value points of upper anterior teeth, obtaining coordinates of each value point; splitting enamel surface of upper anterior teeth into enamel labial surface and enamel lingual surface, splitting dentin surface of upper anterior teeth into dentin labial surface and dentin lingual surface; selecting multiple feature points on each curved surface as value points of the curved surface, and outputting three-dimensional coordinates of the value points; Step three: calculating NURBS control points according to value point coordinates, generating NURBS curved surface through the control points; generating NURBS control points of the curved surface through reverse calculation, and generating NURBS curved surface of enamel labial surface, NURBS curved surface of dentin labial surface, NURBS curved surface of dentin lingual surface and NURBS curved surface of enamel lingual surface respectively; Step four: discretizing NURBS curved surface to generate thickness information of any point of enamel; for any point on NURBS curved surface of enamel labial surface or enamel lingual surface, if the minimum distance between the point and NURBS curved surface of dentin labial surface and NURBS curved surface of dentin lingual surface is not equal, the minimum value of the two distances is the corresponding enamel thickness of the point.

2. The method of claim 1, wherein the method is for measuring the enamel thickness of any point on the surface of the upper incisors. In step two, 20 feature points are selected on each curved surface as value points of the curved surface.

3. The method of claim 1, wherein the method is used for measuring the enamel thickness of any point on the surface of the upper anterior teeth. In step two, the value points of each curved surface are selected as follows: a reference plane corresponding to the curved surface is established, a first plane orthogonal to the reference plane is generated through the most convex point on the curved surface, a second plane orthogonal to the reference plane is generated through the intersection point of the most edge of the curved surface and the reference plane, and the first plane and the second plane are parallel; one or more planes are selected between the first plane and the second plane, which are the third plane, the Nth plane, and the intersection line endpoints of each plane and the corresponding curved surface are the value points, and one or more points with the smallest curvature on each intersection line are the value points.

4. The method of claim 1, wherein the method is used for measuring the enamel thickness of any point on the surface of the upper anterior teeth. In step two, the value points of each curved surface are selected as follows: for the enamel labial surface, a plane through the dental long axis and parallel to the incisal edge is established as a reference plane, a plane orthogonal to the reference plane is generated through the most convex point of the enamel labial surface, and the plane is denoted as f1; a plane orthogonal to the reference plane is generated through the incisal edge, and the plane is denoted as f4; f1 is translated by 2mm to generate f2, and f4 is translated by 2mm to generate f3; the intersection line of f1-f4 and the enamel labial surface is denoted as c1-c4; the two end points and three points with the smallest curvature on c1-c4 are taken as the value points of the enamel labial surface, and there are 20 points in total; the value points on the dentin labial surface, the dentin lingual surface and the enamel lingual surface are selected in the same way.

5. The method of claim 1, wherein the method is used for measuring the enamel thickness of any point on the facial surface of an upper incisor tooth. In step four, the four curved surfaces are discretized into point clouds through NURBS curved surface equation, and for any point on a NURBS curved surface, the corresponding enamel thickness of the point is determined according to the relationship between the minimum distance between the point and the other three NURBS curved surfaces.

6. The method of claim 1, wherein the method is for measuring the enamel thickness of any point on the surface of an upper incisor tooth. In step four, the four curved surfaces are discretized into 10000 discrete point clouds through NURBS curved surface equation.

7. The method of claim 1, wherein the method is for measuring the enamel thickness of any point on the surface of an upper incisor tooth. In step four, for any point on the enamel labial or enamel lingual NURBS surface, if the minimum distance to the dentin labial and dentin lingual NURBS surfaces is equal, then a straight line orthogonal to the reference plane corresponding to the NURBS surface of the point is drawn through the point, and the distance between the intersection of the straight line and the other enamel NURBS surface and the point is the corresponding enamel thickness of the point.

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