A method for measuring the amount of bone grinding of alveolar bone before mandibular implant planning

Abstract

The application discloses a kind of mandible implant plan preoperative alveolar bone bone grinding amount measurement method, comprising the following steps: through the sagittal section image acquisition panoramic volume data of crown and mandible junction;According to the relationship selection implant site in slice image and draw central axis;Extract only including mandible tissue area image;Calculate mandible tissue contour;In mandible contour chart, with the intersection of central axis and the top end of mandible contour chart as fixed point, with the line segment of preset length as the perpendicular line segment of central axis, so that the perpendicular line segment any endpoint and buccal side tongue side bone in mandible contour intersect, the straight line that the perpendicular line segment is located is recorded as bone grinding cutoff line;Fixed point to the distance of bone grinding cutoff line is recorded as bone grinding depth;Determine the position of mandibular nerve canal to calculate the distance from bone grinding cutoff line to mandibular nerve canal;Mandible contour chart, central axis, bone grinding depth value are output as bone grinding amount information.The application improves bone grinding amount measurement efficiency and precision.

Description

Technical Field

[0001] This invention relates to the field of bone reduction measurement, and more specifically, to a method for measuring alveolar bone reduction before mandibular implant surgery. Background Technology

[0002] Clinical studies have shown that after a period of tooth loss in the jawbone, due to the healing of the tooth socket, mechanical stress damage, and the influence of muscle attachment, a sharp, mountain-shaped cortical bone gradually forms at the top of the alveolar ridge at the site of tooth loss. During implant surgery, because this mountain-shaped bone structure is relatively thin and the cortical bone is brittle, direct implant placement can easily cause mandibular bone fractures, leading to implant failure. Therefore, dentists need to manually calculate the amount of alveolar bone to be removed before surgery to avoid bone fractures during the implantation process.

[0003] Currently, the entire process of calculating bone reduction is done manually by doctors, which is extremely time-consuming, and the accuracy is easily affected by individual differences among doctors. Firstly, finding a cross-sectional image perpendicular to the mandible at the implant site using arbitrary multiplanar reconstruction in CBCT volumetric data is very difficult in three-dimensional space. Secondly, after selecting the midline, the distance perpendicular to this midline within the mandible needs to be measured manually by the doctor. There are many lines perpendicular to this midline, requiring repeated attempts to find a suitable width for the cross-section. Thirdly, the final bone reduction amount can only be measured manually after the above conditions are determined. These steps consume a significant amount of the doctor's time; and due to differences in individual doctor experience and fatigue, spatial errors are unavoidable, leading to inaccurate measurement results. Currently, there is no relevant technology to study methods for measuring mandibular alveolar bone reduction. Summary of the Invention

[0004] To overcome the shortcomings of low efficiency and poor accuracy in the traditional bone reduction measurement in the prior art, this invention provides a method for measuring alveolar bone reduction before mandibular implant surgery.

[0005] The primary objective of this invention is to solve the aforementioned technical problems. The technical solution of this invention is as follows: A method for measuring alveolar bone reduction before mandibular bone implant surgery includes the following steps: S1: Obtain a sagittal section image of the junction between the crown and the mandible, and use the sagittal section image to obtain panoramic volume data; S2: Select the slice image where the implant site is located in the panoramic volume data according to the occlusal relationship, and draw the midline in the selected slice image according to the morphology of the adjacent teeth of the implant site. S3: Extract images from slice images that depict the midline, including only the mandibular tissue region; S4: Calculate the mandibular tissue contour based on the extracted mandibular tissue region image; S5: In the mandibular contour map, the intersection of the central axis and the top of the mandibular contour map is taken as the fixed point. A pre-set length line segment is used as the perpendicular line segment of the central axis, such that any endpoint of the perpendicular line segment intersects the buccal and lingual bones in the mandibular contour. The straight line where the perpendicular line segment is located is called the bone grinding cutoff line. The distance from the fixed point to the bone grinding cutoff line is called the bone grinding depth. S6: Determine the location of the mandibular nerve canal using an active contour model in the mandibular contour map; calculate the distance from the mortise cutoff line to the mandibular nerve canal; S7: Output the mandibular contour map, midline, and bone grinding depth as bone grinding amount information.

[0006] Furthermore, the specific steps for obtaining panoramic volume data using the sagittal cross-sectional image are as follows: The dental arch curve is delineated in the sagittal cross-sectional image. The dental arch curve is sampled at equal intervals. At each sampling point, the perpendicular line of the tangent to the dental arch curve is calculated. The volume data in the sagittal cross-sectional image is cut with the perpendicular line as the cutting line to obtain a sequence of slice images. The sequence of slice images is used to generate panoramic volume data in sequence.

[0007] Furthermore, step S3, which involves extracting an image from the slice image containing only the mandibular tissue region, is specifically as follows: S301: Perform image thresholding segmentation on the sliced ​​image; S302: Remove regions in the segmentation result where the pixel value in the continuous space is less than a preset value; S303: Calculate the centroid of the connected regions in the segmentation result, remove the regions whose centroid spatial position is greater than half the height of the slice image, and retain the bone tissue image of the mandibular region.

[0008] Furthermore, in step S301, the CT value of bone tissue is used as the image segmentation threshold.

[0009] Furthermore, the active contour model is the Snake model.

[0010] Furthermore, step S4, which calculates the mandibular tissue contour based on the extracted mandibular tissue region image, is as follows: S401: Using the mandibular bone tissue from step S3 as a mask, perform dilation and erosion operations on the bone tissue image to obtain different bone tissue mask images; S402: Perform AND, OR, and NOT operations on the mandibular tissue mask image to obtain a mandibular mask image; S403: Extract the contour of the masked image of the mandible and filter the extracted contour coordinates to obtain the filtered mandibular boundary contour.

[0011] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention obtains slice images of implantation sites through panoramic volume data, extracts the mandibular contour by drawing the central axis and using morphological methods, and obtains bone reduction information by drawing perpendicular segments of the central axis using line segments of preset length, thereby improving the efficiency and accuracy of bone reduction measurement. Attached Figure Description

[0012] Figure 1 This is a flowchart of the method of the present invention.

[0013] Figure 2 This is a slice image of the implantation site.

[0014] Figure 3 This is a schematic diagram of the central axis drawn on the sliced ​​image.

[0015] Figure 4 This is a segmentation diagram of the tissue region of the mandible.

[0016] Figure 5 Masked image of mandibular bone tissue Figure 6 This is an image showing the erosion result of a masked image of the mandibular bone tissue.

[0017] Figure 7 This is a diagram of the jawbone after expansion.

[0018] Figure 8 This is a schematic diagram of the detected mandibular nerve foramen.

[0019] Figure 9 This is a schematic diagram showing the amount of bone reduction information. Detailed Implementation

[0020] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0022] Example 1 Using a set of 512-512-410 body data reconstructed by Kava dental CBCT as an example, the present invention will be further described in detail. It should be noted that the scope of this invention is not limited to Kava dental equipment; it is also applicable to other equipment. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] like Figure 1 As shown, a method for measuring alveolar bone reduction before mandibular implant surgery includes the following steps: S1: Obtain a sagittal cross-sectional image of the connection between the crown and the mandible. Draw the dental arch curve in the sagittal cross-sectional image. Sample the dental arch curve at equal intervals. Calculate the perpendicular line of the tangent of the dental arch curve at each sampling point. Use the perpendicular line as the cutting line to cut the volume data where the sagittal cross-sectional image is located to obtain a sequence of slice images. The sequence of slice images are used to generate panoramic volume data in sequence. More specifically, from the 512-512-410 volume data, a sagittal section image of the intersection of the top of the mandible and the bottom of the crown is selected. The dental arch curve is drawn on this image. The drawn dental arch is reconstructed using a cubic spline to obtain a smooth dental arch curve. Samples are taken at equal intervals on this dental arch curve, with an interval of one pixel, to obtain all sampling points. The vertical line perpendicular to the tangent of the dental arch curve is calculated at the coordinate position of the sampling point. The volume data is cut along the vertical line to obtain a sequence of slice images. The sequence of slice images is arranged in one go to generate panoramic volume data. S2: In the panoramic volumetric data, select the slice image where the implant site is located based on the occlusal relationship. Based on the morphology of the teeth adjacent to the implant site, draw the midline in the selected slice image; for example... Figure 2 The image shown is a slice image of the implantation site.

[0024] like Figure 3 The image shown is a sliced ​​image with its central axis drawn on it. Figure 4 The results of segmenting the mandibular bone tissue region are shown.

[0025] S3: Extract images from slice images that depict the midline, including only the mandibular tissue region; Specifically, this includes: S301: Using the CT value of bone tissue as the image segmentation threshold, the slice image is segmented using image thresholding; S302: Remove regions in the segmentation result where the pixel value in the continuous space is less than a preset value; S303: Calculate the centroid of the connected regions in the segmentation result, remove the regions whose centroid spatial position is greater than half the height of the slice image, and retain the bone tissue image of the mandibular region.

[0026] More specifically, the sliced ​​image is first thresholded for segmentation, using the CT value of bone tissue as the threshold, to obtain an initial bone segmentation result. Then, regions with fewer than 600 pixels in continuous space within the segmentation result are extracted to reduce the influence of noise and non-jawbone tissue. Next, the centroids of all connected regions in the segmentation result are calculated, and regions with centroids spatially greater than half the image height are retained, retaining only the bone tissue image of the mandibular region.

[0027] S4: Calculate the mandibular tissue contour based on the extracted mandibular tissue region image; Specifically, this includes: S401: using the mandibular bone tissue from step S3 as a mask (e.g., ... Figure 5 The image shown is a mask of mandibular bone tissue. Dilation and erosion operations are performed on the bone tissue image to obtain different bone tissue mask images. like Figure 6 The image shown is the erosion result of a masked image of the mandibular bone tissue. Figure 7 The image shown is a contour diagram of the expanded jawbone.

[0028] S402: Perform AND, OR, and NOT operations on the mandibular tissue mask image to obtain a mandibular mask image; S403: Extract the contour of the masked image of the mandible and filter the extracted contour coordinates to obtain the filtered mandibular boundary contour.

[0029] S5: In the mandibular contour map, the intersection of the central axis and the top of the mandibular contour map is taken as the fixed point. A pre-set length line segment is used as the perpendicular line segment of the central axis, such that any endpoint of the perpendicular line segment intersects the buccal and lingual bones in the mandibular contour. The straight line where the perpendicular line segment is located is called the bone grinding cutoff line. The distance from the fixed point to the bone grinding cutoff line is called the bone grinding depth. like Figure 8 The diagram shown is a schematic of the detected mandibular nerve foramen.

[0030] S6: Using an active contour model, such as the Snake model, in the mandibular contour map, determine the location of the mandibular nerve canal; calculate the distance from the mortise cutoff line to the mandibular nerve canal; S7: Output the mandibular contour map, midline, and bone grinding depth as bone grinding amount information.

[0031] like Figure 9 The diagram shows the bone reduction information. Line AB is the central axis, line segment xy is the line segment of a preset length, points x and y are the intersections of line segment xy (i.e., the perpendicular line segment) and the buccal and lingual bones in the mandibular contour, line CD is the line containing line segment xy, i.e., the bone reduction cutoff line, point P is the foot of the perpendicular, i.e., the intersection of the central axis and the bone reduction cutoff line, the distance from point O to the bone reduction cutoff line is the length of OP, i.e., the bone reduction depth, and the effective height PB is the distance from the bone reduction cutoff line to the mandibular canal.

[0032] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring alveolar bone reduction before mandibular bone implantation, characterized in that, Includes the following steps: S1: Obtain a sagittal cross-sectional image of the junction between the crown and the mandible, and use the sagittal cross-sectional image to obtain panoramic volume data; S2: Select the slice image where the implant site is located in the panoramic volume data according to the occlusal relationship, and draw the midline in the selected slice image according to the morphology of the adjacent teeth of the implant site. S3: Extract images from slice images that include only the mandibular tissue region from the plotted midline; S4: Calculate the mandibular tissue contour based on the extracted mandibular tissue region image; S5: In the mandibular contour map, the intersection of the central axis and the top of the mandibular contour map is taken as the fixed point. A pre-set length line segment is used as the perpendicular line segment of the central axis, such that any endpoint of the perpendicular line segment intersects the buccal and lingual bones in the mandibular contour. The straight line where the perpendicular line segment is located is recorded as the bone grinding cutoff line. The distance from the fixed point to the bone grinding cutoff line is recorded as the bone grinding depth value. S6: Determine the location of the mandibular nerve canal using an active contour model in the mandibular contour map; calculate the distance from the mortise cutoff line to the mandibular nerve canal; S7: Output the mandibular contour map, midline, and bone grinding depth as bone grinding amount information.

2. The method for measuring alveolar bone reduction before mandibular bone implantation according to claim 1, characterized in that, The specific steps for obtaining panoramic volume data using the sagittal cross-sectional image are as follows: The dental arch curve is delineated in the sagittal cross-sectional image. The dental arch curve is sampled at equal intervals. At each sampling point, the perpendicular line of the tangent to the dental arch curve is calculated. The volume data in the sagittal cross-sectional image is cut with the perpendicular line as the cutting line to obtain a sequence of slice images. The sequence of slice images is used to generate panoramic volume data in sequence.

3. The method for measuring alveolar bone reduction before mandibular bone implantation according to claim 1, characterized in that, Step S3 involves extracting an image containing only the mandibular tissue region from the slice image drawn along the midline. The specific steps are as follows: S301: Perform image thresholding segmentation on the sliced ​​image; S302: Remove regions in the segmentation result where the pixel value in the continuous space is less than a preset value; S303: Calculate the centroid of the connected regions in the segmentation result, remove the regions whose centroid spatial position is greater than half the height of the slice image, and retain the bone tissue image of the mandibular region.

4. The method for measuring alveolar bone reduction before mandibular bone implantation according to claim 3, characterized in that, In step S301, the CT value of bone tissue is used as the image segmentation threshold.

5. The method for measuring alveolar bone reduction before mandibular bone implantation according to claim 1, characterized in that, The active contour model is the Snake model.

6. The method for measuring alveolar bone reduction before mandibular bone implantation according to claim 1, characterized in that, Step S4, which calculates the mandibular tissue contour based on the extracted mandibular tissue region image, is as follows: S401: Using the mandibular bone tissue from step S3 as a mask, perform dilation and erosion operations on the bone tissue image to obtain different bone tissue mask images; S402: Perform AND, OR, and NOT operations on the mandibular tissue mask image to obtain a mandibular mask image; S403: Extract the contour of the masked image of the mandible and filter the extracted contour coordinates to obtain the filtered mandibular boundary contour.

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