An occlusal detection and analysis system integrating two-dimensional images of dental arches and an implementation method

Abstract

The present invention discloses a bite detection and analysis system integrating two-dimensional images of dental arches and an implementation method. The system includes: a flexible force sensor for detecting the magnitude of the biting force; a support frame for fixing the flexible force sensor and fixedly connected to one end of a transmission handle; a data transmission circuit is arranged inside the transmission handle to transmit the data of the flexible force sensor to a display terminal; a display terminal for displaying the biting force distribution according to the received data of the flexible force sensor; and an optical sensing device for acquiring two-dimensional images of dental arches. The bite detection and analysis system combined with the flexible force sensor, the support frame, the transmission handle, and the display terminal of the present invention can achieve the advantages of rapid extraction of the two-dimensional shape of the dental arch, good adaptability, high accuracy, and low cost, saving the time for medical staff to compare and process later and reducing the quantization error of the bite detection and analysis system.

Description

Technical Field

[0001] The present invention relates to the technical field of image processing, and particularly relates to a bite detection and analysis system and an implementation method for fusing two-dimensional images of dental arches. Background Art

[0002] Occlusion science, as a basic discipline in stomatology and an applied discipline in oral clinical practice, runs through the whole process of diagnosis, treatment, and evaluation of oral diseases. Therefore, it is particularly important to accurately quantify and evaluate occlusion. Currently, digital occlusion analysis systems represented by T-Scan (Tekscan.Inc, USA) are increasingly widely used in clinical practice due to their functions such as quantifying and evaluating occlusion conditions.

[0003] The existing digital occlusion analysis systems mainly use indicators such as the percentage of the total biting force occupied by different teeth and the imbalance degree of the left and right biting forces for occlusion evaluation. These all rely on the accuracy of the dental arch modeling by the occlusion analysis system.

[0004] Currently, the main methods for dental arch modeling are divided into two-dimensional modeling methods and three-dimensional modeling methods. The method for establishing a two-dimensional dental arch model generally takes an ideal dental arch curve as a benchmark, calculates the tooth positions by inputting the width of the central incisor and then combining the mesiodistal widths of all teeth. The defect of this method is that it cannot accurately fit the tooth positions of patients with deformities, and the process of measuring the mesiodistal widths of each tooth is also relatively cumbersome. The other method is to import a three-dimensional oral model into the system. Although there are many studies on the method of segmenting the dental arch in the three-dimensional model, the current methods still have problems such as large computational amount and large segmentation error. In addition, it is necessary to purchase an oral three-dimensional scanner or a CBCT scanning device, which increases the usage cost. For the problems in the related technology, no effective solution has been proposed yet.

[0005] The determination of tooth positions is particularly important for an oral occlusion analysis system. This helps doctors determine the actual positions of occlusion abnormal points in teeth. However, the existing central incisor width method and the method of importing a three-dimensional oral model respectively have problems such as inaccurate dental arch models, cumbersome measurement, and high cost. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies existing in the prior art, and propose a bite detection and analysis system and an implementation method for fusing two-dimensional images of dental arches. The bite detection and analysis system processes the two-dimensional images of the dental arches to quickly and accurately establish a two-dimensional dental arch model, so as to improve the accuracy of subsequent quantitative evaluation.

[0007] The technical solution of the present invention is as follows: A bite detection and analysis system for fusing two-dimensional images of dental arches, comprising:

[0008] A flexible force - sensitive sensor, used to detect the magnitude of the biting force;

[0009] A support frame, used to fix the flexible force - sensitive sensor and fixedly connected to one end of the transmission handle;

[0010] A transmission handle, internally provided with a data transmission circuit, used to transmit the data of the flexible force - sensitive sensor to the display terminal;

[0011] A display terminal, used to display the biting force distribution according to the received data of the flexible force - sensitive sensor;

[0012] An optical sensing device, used to obtain a two - dimensional image of the dental arch.

[0013] Furthermore, the flexible force - sensitive sensor is arranged in a semi - circular area corresponding to the oral occlusion position, and the surface of the semi - circular area is coated with an edible pigment for tooth marking.

[0014] Furthermore, the support frame has a positioning device to keep the relative position of the flexible force - sensitive sensor and the position of the maxillary central incisors fixed.

[0015] Furthermore, the positioning device is an isosceles triangle - shaped raised block, and the axis of symmetry of the triangle is the same as the axis of symmetry of the support frame. When the tip of the positioning device is embedded into the gap between the two maxillary central incisors, it is used for sensor positioning.

[0016] According to another aspect of the present invention, a two - dimensional dental arch modeling method for a bite detection and analysis system including the above - mentioned fused two - dimensional dental arch image is also proposed. The implementation method includes the following steps:

[0017] Step 201. Adjust the patient's body position, select and place a suitable mouth opener and reflector;

[0018] Step 202. Clean and dry the area to be photographed in the oral cavity;

[0019] Step 203. Take a photo of the reflector after determining the composition position;

[0020] Step 204. Use the oral bite detection and analysis system to record the user's bite condition;

[0021] Step 205. Process the collected images and extract the convex hull contour of the entire dental arch;

[0022] Step 206. After the user manually selects the feature point positions, automatically match the bite pressure distribution map with the two - dimensional dental arch model.

[0023] Furthermore, the processing of the collected images in step 205 includes:

[0024] S1. Convert the acquired image Z1 into a grayscale image Z2 using grayscale transformation;

[0025] S2. Select an initial value as the global threshold T. Divide the pixels greater than T into group, and the pixels less than or equal to T into group. The average value of the pixels in and is and, respectively. Thus, a new is obtained. Iterate multiple times until the difference between two T values is less than a predefined parameter;

[0026] S3. Perform morphological opening and closing operations. Use a cross-shaped operator with a radius of 7 to remove the influence of "glitter" reflective areas such as the tongue, and obtain a binary image Z4;

[0027] S4. Start flood filling the binary image Z4 from the point (0, 0). Invert the result of the flood filling to obtain a binary image Z5, and perform a logical OR operation with the original binary image Z4 to obtain an image Z6 with holes filled;

[0028] S5. Convert the image Z6 into a background area (labeled 0) and a foreground area (labeled 1) through morphological dilation and distance transformation. Subtract the two to obtain the unknown area. Execute the watershed algorithm to obtain the points on the edge contour in the image Z7, and label them as -1;

[0029] S6. Take any point P0 on a certain closed contour of the image Z7 as the origin. Calculate the angle α of each point relative to P0, and sort the points according to the size of the angle α. Connect the first point in the sequence to obtain a straight line L, and perform the following operations on the subsequent points. If it is on the right side of the straight line L, discard it; if it is on the left side of the straight line L, connect it as part of the convex hull contour. Each convex hull is used as the area range of each tooth.

[0030] Furthermore, the bite detection and analysis system selects and marks the three points with the maximum pressure values during the biting process. The user refers to the marks of the edible pigment on the teeth and clicks on the positions of the corresponding three feature points on the two-dimensional dental arch image in sequence. According to the user's clicks, the system automatically rotates and scales the two-dimensional dental arch image to make it match the oral pressure distribution map.

[0031] Advantageous effects:

[0032] The present invention combines a bite detection and analysis system composed of a flexible force-sensitive sensor, a support frame, a transmission handle, a display terminal, and an optical sensing device for detecting the magnitude of the biting force, which can achieve the advantages of rapid extraction of the two-dimensional shape of the dental arch, good adaptability, high accuracy, and low cost, saving the time for medical staff in later comparison and processing, and reducing the quantization error of the bite detection and analysis system. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a structural diagram of the bite detection and analysis system in the present invention;

[0035] Figure 2 It is a schematic diagram of the support frame in the bite detection and analysis system of the present invention;

[0036] Figure 3 It is a flowchart of a two-dimensional dental arch modeling method for fusing two-dimensional dental arch images in the present invention;

[0037] Figure 4 It is a schematic diagram of the convex hull detection algorithm in the present invention;

[0038] Figure 5 It is a schematic diagram of a certain oral photography photo in the present invention;

[0039] Figure 6 It is a schematic diagram of the two-dimensional coordinate system of the dental arch model in the present invention.

[0040] Reference numerals in the figure: 101, flexible force sensor; 102, support frame; 103, transmission handle; 104, display device; 105, optical sensing device. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0042] According to an embodiment of the present invention, a bite detection and analysis system for fusing two-dimensional dental arch images is provided.

[0043] As Figure 1 shown, the bite detection and analysis system according to an embodiment of the present invention includes a flexible force sensor 101 for detecting the magnitude of the biting force; a support frame 102 for fixing the flexible force sensor and connecting to the transmission handle; a transmission handle 103 for data transmission between the flexible force sensor and the display terminal; a display device 104 for displaying the distribution of the biting force; and an optical sensing device 105 for obtaining two-dimensional dental arch images.

[0044] Specifically, the flexible force sensor 101 is disposed in a semi-circular region corresponding to the oral occlusion position, and the surface of the semi-circular region is coated with an edible pigment for tooth marking.

[0045] Specifically, the support frame 102 includes a positioning device to keep the flexible force sensor relatively fixed with respect to the position of the maxillary central incisors.

[0046] As Figure 2 shown, the positioning device is an isosceles triangular block protrusion, and the axis of symmetry of the triangle is the same as the axis of symmetry of the support frame. When the tip of the positioning device is embedded into the gap between the two maxillary central incisors, it can be used for sensor positioning.

[0047] According to an embodiment of the present invention, there is also provided a two-dimensional dental arch modeling method for fusing two-dimensional dental arch images, which is used for the above-mentioned occlusion detection and analysis system.

[0048] As Figure 3 shown, according to an embodiment of the present invention, the two-dimensional dental arch modeling method including the occlusion detection and analysis system for fusing two-dimensional dental arch images as described above includes the following steps:

[0049] 201. Adjust the patient's position, select and place a suitable mouth opener and reflector;

[0050] 202. Clean and dry the area to be photographed;

[0051] 203. After determining the composition position, photograph the reflector;

[0052] 204. Use an oral occlusion detection device to record the user's occlusion condition;

[0053] 205. Process the collected images to extract the convex hull contour of the entire dental arch;

[0054] In specific applications, the image processing techniques used in the above step 205 include: grayscale transformation image processing technique, threshold segmentation image processing technique, morphological opening operation and closing operation, watershed algorithm, and convex hull detection and other techniques.

[0055] To facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention will be described in detail below through specific image processing techniques respectively.

[0056] After the oral image is collected, it can be saved on the local disk, and then the image is processed as follows in sequence:

[0057] According to an embodiment of the present invention, the grayscale processing and threshold segmentation are as follows:

[0058] After grayscale processing the image, in this embodiment, an iterative method is used to obtain the optimal threshold: First, an initial value of the average grayscale value T is selected, and the image is segmented by T. All pixels with grayscale values greater than T are classified into the G 1 group, otherwise classified into the G 2 group. Calculate the average grayscale value μ 1 of the pixels in G 2 and μ 1 of the pixels in G 2 Then let the new threshold T 1 =(μ 1 +μ 2 ) / 2, and then assign the value of T 1 to T, and re-segment the original image with T. In this embodiment, a better segmentation effect can be obtained when the threshold is set to 105.

[0059] According to an embodiment of the present invention, the morphological opening operation and closing operation are specifically as follows:

[0060] Perform grayscale processing on the image and perform morphological opening operation. The opening operation involves logical morphological operations on the image. First, erode the image, and then perform a dilation operation on the eroded structure. Since the areas with high humidity in the tooth, tongue, and gum regions have strong reflection. Therefore, the grayscale of these reflective teeth will be greater than that of the normal tooth region. In view of the characteristics of "glitter", a cross-shaped operator with a radius of 7 is used; the operator is the structuring element B, and the image is the set A. Then the opening operation of the structuring element B on the set A is expressed as After performing the opening operation, perform the closing operation to reduce image distortion.

[0061] According to an embodiment of the present invention, the hole filling is specifically as follows:

[0062] To ensure that the foregoing operations do not create holes in the tooth region, hole filling is required. A hole is defined as a background area surrounded by the boundary connected by foreground pixels. The main steps are as follows:

[0063] (1) First, obtain the binary image of the original image after the above-mentioned morphological operation processing;

[0064] (2) Start flood filling the image from the point (0, 0);

[0065] (3) Invert the result after flood filling;

[0066] (4) Perform a logical OR operation on the result images obtained in steps (1) and (3) to finally obtain the hole-filled image.

[0067] According to an embodiment of the present invention, the specific steps of the watershed algorithm are as follows:

[0068] (1) Perform a morphological dilation operation on the binary image obtained in the previous step as the background area;

[0069] (2) Perform a distance transformation on the same binary image as the foreground area;

[0070] (3) Subtract the foreground area from the aforementioned background area to obtain the unknown area;

[0071] (4) Mark all background areas as 0 and then mark all foreground areas as 1;

[0072] (5) Use the watershed algorithm to mark the points on the contour as -1.

[0073] In this embodiment, when using the watershed algorithm to segment different teeth, in order to completely segment the teeth, the divided areas are often small. In this embodiment, the convex hull detection algorithm is used to correct the tooth area, and this is used as the tooth area in the two-dimensional dental arch model.

[0074] According to an embodiment of the present invention, the specific steps of convex hull detection are as follows:

[0075] In this embodiment, the Graham scan method is used to calculate the two-dimensional convex hull of the tooth edge. The best and worst algorithm complexities of this algorithm are both O(nlogn). As Figure 4 shown, the specific steps are as follows:

[0076] (1) P0 to P8 are all randomly generated points in the two-dimensional plane. Then, in the two-dimensional rectangular coordinate system, the point with the smallest ordinate must be a point on the convex hull, such as P0 in the figure;

[0077] (2) Translate the coordinates of all points so that P0 is the origin;

[0078] (3) Calculate the argument α of each point relative to P0 and sort all points in ascending order. When α is the same, the point closer to P0 is ranked first. As Figure 2 The result obtained is P1, P2, P3, P4, P5, P6, P7, P8. From geometric knowledge, the two points P1 and P8 with the largest and smallest α angles must be points on the convex hull.

[0079] (4) Connect P0 and P1 to obtain the straight line L. The P2 point - that is, the point after P1 in the sorting - is used as the current point. See whether the current point is on the right or left side of the straight line L. If it is on the right side of the straight line, perform step (5); if it is on the straight line or on the left side of the straight line, perform step (6).

[0080] (5) If it is on the right side, then the current point is not a point on the convex hull. Take the point after the current position as the current point. Perform step (4);

[0081] (6) The current point is a point on the convex hull. Connect the straight line and execute step (7);

[0082] (7) Check whether the current point is the last element of the calculation result in step (3). If it is the last element, end the whole process of calculation. If it is not the last point, take the point after the current position as the current point.

[0083] 206. After the user manually selects the positions of the feature points, the occlusal pressure distribution map is automatically matched with the two-dimensional dental arch model.

[0084] The specific steps are as follows: The occlusal detection and analysis system selects and marks the three points with the largest pressure values during the occlusion process. The user can refer to the marks of the edible pigment on the teeth and click on the corresponding three position points on the two-dimensional dental arch image in sequence. According to the user's clicks, the system automatically rotates and scales the two-dimensional dental arch image to make it match the oral pressure distribution map.

[0085] As Figure 5 and Figure 6 shown, calculate the tangent line on the edge of the convex hull where the central incisor point is located. This tangent line L1 is the X-axis of the two-dimensional rectangular coordinate system, and the straight line L2 perpendicular to the straight line L1 and passing through the central incisor point is the Y-axis of the two-dimensional rectangular coordinate system.

[0086] Connect the points with the smallest X coordinates on each convex hull in sequence, and calculate the distances W 01 、W 12 、W 23 etc. At the same time, taking the mesiodistal width of the teeth in dental anatomy as the threshold, start marking from the convex hull with the minimum coordinate on the X-axis. When the distance between two points exceeds twice the mesiodistal width threshold of the teeth, it can be considered that the tooth is missing and the marking can be skipped.

[0087] In summary, by means of the method proposed by the present invention, rapid modeling of the two-dimensional dental arch model can be realized, which has the advantages of good adaptability, high accuracy, low cost, etc., making oral photography, as one of the common diagnostic items, more clinically valuable. At the same time, the two-dimensional dental arch image can be converted into a segmented two-dimensional dental arch model, improving the accuracy of the later quantitative analysis of occlusal data and saving the time for medical staff to compare and process later.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bite detection and analysis system that integrates two-dimensional images of dental arches, characterized in that, it includes: A flexible force sensor for detecting the magnitude of the biting force; A support for fixing the flexible force sensor and fixedly connected to one end of the transmission handle; A transmission handle with a data transmission circuit inside for transmitting the data of the flexible force sensor to the display terminal; A display terminal for displaying the biting force distribution according to the received data of the flexible force sensor; An optical sensing device for obtaining two-dimensional images of dental arches; Based on the two-dimensional dental arch modeling method adopted by the bite detection and analysis system, it includes the following steps: Step 201. Adjust the patient's position, select and place a suitable mouth opener and reflector; Step 202. Clean and dry the area to be photographed inside the oral cavity; Step 203. Take a photo of the reflector after determining the composition position; Step 204. Use the oral bite detection and analysis system to record the user's biting situation; Step 205. Process the collected images to extract the convex hull contour of the entire dental arch. Processing the collected images includes: S1. Use grayscale transformation to convert the collected image Z1 into a grayscale image Z2; S2. Select an initial value as the global threshold T, and assign the pixels greater than T to the G 1 group, and assign the pixels less than or equal to T to the G 2 group. The average pixel values of G 1 and G 2 are μ 1 and μ 2 respectively. Thus, a new threshold T 1 =(μ 1 +μ 2 ) / 2 is obtained. Iterate multiple times until the difference between the two thresholds is less than a predefined parameter. At this time, re-segment the grayscale image Z2 using the new threshold to obtain the threshold-segmented image Z3; S3. Perform morphological opening and closing operations on the image Z3, and use a cross-shaped operator with a radius of 7 to remove the influence of "glitter" reflection areas such as the tongue to obtain a binary image Z4; S4. Start flood filling the binary image Z4 from the coordinate point (0,0), take the inverse of the flood filling result, obtain a binary image Z5, and perform a logical OR operation with the original binary image Z4 to obtain an image Z6 after hole filling; S5. Convert the image Z6 into a background area (marked as 0) and a foreground area (marked as 1) through morphological dilation and distance transformation. Subtract the two to obtain the unknown area, perform the watershed algorithm to obtain the points on the edge contour in the image Z7, and mark them as -1; S6. Take any point P0 on a certain closed contour of the image Z7 as the origin, calculate the angle α of each point relative to P0, and sort the points according to the size of the angle α. Connect the first point in the order to obtain a straight line L, and perform the following operations on the subsequent points. If it is on the right side of the straight line L, discard it. If it is on the left side of the straight line L, connect it as part of the convex hull contour. Each convex hull is used as the area range of each tooth; Step 206. After the user manually selects the position of the feature points, automatically match the bite pressure distribution map with the two-dimensional dental arch model.

2. The bite detection and analysis system that integrates two-dimensional images of dental arches according to claim 1, characterized in that, The flexible force sensor is arranged in a semi-circular area corresponding to the oral bite position, and the surface of the semi-circular area is coated with edible pigment for tooth marking.

3. The bite detection and analysis system that integrates two-dimensional images of dental arches according to claim 1, characterized in that, The support has a positioning device to keep the flexible force sensor relatively fixed with respect to the position of the maxillary central incisor.

4. The bite detection and analysis system that integrates two-dimensional images of dental arches according to claim 3, characterized in that, The positioning device is an isosceles triangle-shaped protrusion, and the axis of symmetry of the isosceles triangle-shaped protrusion is the same as that of the support frame. When the tip of the positioning device is embedded into the gap between the two maxillary central incisors, it is used for sensor positioning.

5. A two-dimensional dental arch modeling method for a bite detection and analysis system including a fused dental arch two-dimensional image as described in any one of claims 1 to 4, characterized in that the bite detection and analysis system selects and marks three points with the maximum pressure values during the biting process, and the user refers to the marks of the edible pigment on the teeth and clicks on the positions of the corresponding three feature points on the two-dimensional dental arch image in sequence; the system automatically rotates and scales the two-dimensional dental arch image according to the user's clicks so as to match the oral pressure distribution map.

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