Method for manufacturing a dental grinding slice of a specified image section in micro-CT

Abstract

The present invention relates to the field of imaging technology, and discloses a method for fabricating a tooth grinding slice of a specified image section in micro-CT. The method includes the following steps: preserving freshly extracted teeth in a 0.5% thymol solution; selecting target teeth to take micro-CT; importing the Dicom format data of the micro-CT into medical image processing software to three-dimensionally reconstruct a 3D tooth model. In this example, the tomographic image in the lower left corner of the attached figure is selected as an example; the method for fabricating a tooth grinding slice of a specified image section in micro-CT according to the present invention utilizes 3D modeling technology and 3D printing technology to fabricate a 3D printed guide plate for guiding the cutting direction of dental tissue, realizing the accurate transfer from the micro-CT image section to the actual dental tissue surface. By combining the tooth grinding slice fabrication technology with the 3D printed guide plate, the tooth tissue slice is selectively polished in a single direction, effectively protecting the target tissue surface and realizing the accurate transfer from the micro-CT image section to the ultra-thin tooth grinding slice.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and specifically to a method for manufacturing a tooth grindstone for a specified image section in micro-CT. Background Art

[0002] Dental caries is a chronic progressive destructive disease that occurs in the hard tissues of teeth under the influence of multiple factors mainly bacteria. When dental enamel caries progresses deep into dentin, due to the acid production of bacteria, the affected dentin can generally be divided into four layers according to tissue morphology, demineralization degree, and bacterial invasion. For clinicians, it is of great significance to explore the gray-scale differences of different layers of carious dentin in X-ray images, which may help clinicians more accurately distinguish the range of carious dentin layers by combining commonly used medical imaging techniques in clinical practice, so as to guide clinicians to safely and accurately remove carious tissues in clinical practice. Tooth grindstone is an ideal technical means to observe and study the structure of carious dentin at present. Under a transmission light microscope, researchers can clearly distinguish and mark the range of different carious dentin layers on the ultra-thin grindstone of the target tissue surface. By scaling and overlapping the high-resolution micro-CT tomographic image corresponding to the grindstone in equal proportion, the layer marks of carious dentin can be mapped onto the tomographic image, and finally the gray-scale differences of different layers of carious dentin can be analyzed in software.

[0003] The currently commonly used method is to first cut the tooth along the carious part under visual observation, then take a micro-CT of the remaining tooth tissue block with the required tissue surface, and finally scale and overlap the image of the required tissue surface with the micro-CT tomographic image of this surface, and map the range of the carious dentin layer on the tissue surface onto the tomographic image of this surface for gray-scale difference analysis. The main disadvantages of this method are threefold: First, before taking the micro-CT, researchers lack an understanding of the internal information of the tooth lesion, and are unclear about the location and scope of the lesion. Therefore, there is a certain blindness in selecting the target tissue surface. If it is found after cutting that the selected tooth tissue surface does not meet the research requirements, it will cause irreversible damage to the sample and waste of human and material resources; Second, the basic principle of micro-CT is that X-rays pass through an object from all directions, and a computer program analyzes and measures all attenuated X-rays. The tissue content of the remaining tooth tissue block after cutting is quite different from that of the intact tooth, and the reduction of X-rays passing through the tissue will be significantly reduced, resulting in a significant difference between the image information of this layer and the image information presented when the tooth is intact, which is not conducive to obtaining scientific research results. Third, the current technical method can only obtain large pieces of tooth tissue with the target tissue surface, rather than ultra-thin grindstones of non-target tissue surfaces. Therefore, such specimens cannot be used for observation under a transmission light microscope, cannot accurately mark the range of different carious dentin layers, and cannot ensure the accuracy of the marks mapped onto the tomographic image.

[0004] Therefore, it is of great significance to invent a method for taking micro-CT without damaging the tooth tissue and making a tooth grinding slice of a specified image section in the micro-CT according to research needs, so as to improve the sample utilization rate and experimental success rate, enhance the accuracy of marking different levels of carious dentin, and ensure the scientificity and standardization of the research on the gray-scale difference between different levels of carious dentin.

[0005] To solve this technical problem, there is an urgent need for a method for making a tooth grinding slice of a specified image section in the micro-CT to solve the above deficiencies. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the present invention provides a method for making a tooth grinding slice of a specified image section in the micro-CT, which solves the problems existing in the current method, such as blindly selecting the target tissue surface, the integrity of the tooth being damaged before taking the micro-CT, and it is difficult to accurately mark the range of carious dentin levels on a large opaque tissue sample.

[0007] The present invention provides the following technical solution: A method for making a tooth grinding slice of a specified image section in the micro-CT, the method comprising the following steps:

[0008] Step 1: Preserve the freshly extracted tooth in a 0.5% thymol solution;

[0009] Step 2: Select the target tooth to take micro-CT;

[0010] Step 3: Import the Dicom format data of the micro-CT into medical image processing software, and three-dimensionally reconstruct the 3D tooth model. In this example, the lower left corner tomographic image is selected as an example;

[0011] Step 4: Draw an analysis cylinder outside the 3D tooth model. The size of the cylinder should be such that it can completely accommodate the tooth model. The distance between each surface of the cylinder and the tooth surface should be not less than 4 mm to ensure that the 3D printing guide plate has sufficient thickness and strength;

[0012] Step 5: Perform a Boolean subtraction operation on the cylinder and the tooth model to obtain a hollow cylinder containing the tooth structure;

[0013] Step 6: Observe the tomographic images involving caries in the coronal or sagittal image window to determine the tomographic images or tissue surfaces included in the study;

[0014] Step 7: Cut the selected layer in the cross-sectional image window to obtain a hollow cylinder divided into two halves, that is, the 3D printing guide plate;

[0015] Step 8: Save and output the two respectively as STL files;

[0016] Step 9: Perform high-precision 3D printing based on the STL file, and select a coated soft rubber material with a softness of 70, taking into account both the strength and flexibility of the guide plate;

[0017] Step 10: Select the corresponding 3D guide plate and embed the tooth in it in the corresponding posture to fix the positional relationship of the tooth in three-dimensional space;

[0018] Step 11: Use a diamond saw blade to cut the tooth along the 3D guide plate under the condition of water cooling until the tissue surface of the tooth is completely parallel to the 3D guide plate. This tissue surface of the tooth is the image section determined on the micro-CT image in Step 6;

[0019] Step 12: Remove the tooth from the guide plate and use a diamond saw blade to cut the tooth into thin slices from the opposite direction under the condition of water cooling;

[0020] Step 13: Manually polish the slices on an oilstone. When polishing, always keep the cutting surface in contact with the oilstone and the target tissue surface of the tooth in contact with the finger, and perform repeated polishing in a single direction;

[0021] Step 14: Observe the changes in the polished slices. Stop polishing until they become semi-transparent and measure their thickness until the thickness reaches about 50 μm to meet the basic conditions for microscopic observation;

[0022] Step 15: Put the prepared polished slices into absolute ethanol for cleaning and dehydration for 10 - 15 minutes, and then put them into xylene for clearing for 10 - 15 minutes;

[0023] Step 16: Finally, seal the slices with neutral gum for microscopic observation.

[0024] Preferably, the resolution of the micro-CT scan is below 20 μm.

[0025] Preferably, one side of the thin slice in Step 12 is the target tissue surface of the tooth obtained in Step 11, and the other side is the cutting surface.

[0026] Preferably, the temperature of the thymol solution is maintained at 4°C.

[0027] Preferably, the thickness of the thin slice in Step 12 is 1 - 2 mm.

[0028] Preferably, the prepared polished slices in Step 15 are put into absolute ethanol for cleaning and dehydration for 10 - 15 minutes, and then put into xylene for clearing for 10 - 15 minutes.

[0029] Compared with the prior art, the present invention has the following beneficial effects: The method for fabricating a tooth grinding slice for a specified image section in a micro-CT uses 3D modeling technology and 3D printing technology to fabricate a 3D printed guide plate for guiding the cutting direction of dental tissue, achieving an accurate transfer from the micro-CT image section to the actual dental tissue surface. By combining the tooth grinding slice fabrication technology with the 3D printed guide plate, the dental tissue slices are selectively polished in a single direction, effectively protecting the target tissue surface and achieving an accurate transfer from the micro-CT image section to the ultra-thin tooth grinding slice. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects, and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 It is a 3D model diagram of a three-dimensional reconstructed tooth in the present invention;

[0032] Figure 2 It is a diagram of a hollow cylinder containing a tooth structure in the present invention;

[0033] Figure 3 It is a schematic diagram of the cutting of the hollow cylinder in the present invention;

[0034] Figure 4 It is a schematic diagram of the hollow semi-cylindrical structure in the present invention;

[0035] Figure 5 It is a schematic diagram of the cutting surface after the hollow semi-cylinder is placed into the tooth in the present invention;

[0036] Figure 6 It is a diagram of the actual tissue surface, image section surface, and ultra-thin grinding slice in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The drawings are only for illustrative purposes and show only schematic diagrams, not physical diagrams, and should not be construed as limiting the present patent. For a better illustration of the specific embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. For those skilled in the art, it is understandable that some well-known structures, components, and their descriptions in the drawings may be omitted. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "arrangement" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a movable connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0039] Please refer to Figure 1-6 , a method for making a tooth grinding slice of a specified image section in a micro-CT, the method comprising the following steps:

[0040] Step 1: Preserve the freshly extracted tooth in a 0.5% thymol solution;

[0041] Step 2: Select the target tooth to take a micro-CT;

[0042] Step 3: Import the Dicom format data of the micro-CT into medical image processing software, and three-dimensionally reconstruct the 3D tooth model. In this example, the lower left corner tomographic image is selected as an example;

[0043] Step 4: Draw an analysis cylinder outside the 3D tooth model. The size of the cylinder is based on being able to completely accommodate the tooth model, and the distance between each surface of the cylinder and the tooth surface is not less than 4 mm to ensure that the 3D printing guide plate has sufficient thickness and strength;

[0044] Step 5: Perform a Boolean subtraction operation on the cylinder and the tooth model to obtain a hollow cylinder containing the tooth structure;

[0045] Step 6: Observe the tomographic images involving caries in the coronal or sagittal image window to determine the tomographic images or tissue surfaces included in the study;

[0046] Step 7: Cut the selected layer in the cross-sectional image window to obtain a hollow cylinder divided into two halves, that is, the 3D printing guide plate;

[0047] Step 8: Save and output the two respectively as STL files;

[0048] Step 9: Perform high-precision 3D printing based on the STL file, and select a coated soft glue material with a softness of 70 to balance the strength and flexibility of the guide plate;

[0049] Step 10: Select the corresponding 3D guide plate to embed the tooth in the corresponding posture, and fix the positional relationship of the tooth in three-dimensional space;

[0050] Step Eleven: Use a diamond saw blade to cut the tooth along the 3D guide plate under water cooling until the tissue surface of the tooth is completely parallel to the 3D guide plate. This tissue surface of the tooth is the image section determined on the micro-CT image in Step Six.

[0051] Step Twelve: Remove the tooth from the guide plate and use a diamond saw blade to cut the tooth into thin slices from the opposite direction under water cooling.

[0052] Step Thirteen: Manually polish the slices on an oilstone. During polishing, always keep the cutting surface in contact with the oilstone and the target tissue surface of the tooth in contact with the finger, and perform repeated polishing in a single direction.

[0053] Step Fourteen: Observe the changes in the polished slices. Measure the thickness until it reaches a semi-transparent state and stop when the thickness reaches about 50 μm to meet the basic conditions for microscopic observation.

[0054] Step Fifteen: Put the prepared polished slices into absolute ethanol for cleaning and dehydration for 10 - 15 minutes, and then put them into xylene for clearing for 10 - 15 minutes.

[0055] Step Sixteen: Finally, seal the slices with neutral balsam for microscopic observation.

[0056] Among them, the resolution of the micro-CT scan is below 20 μm.

[0057] Among them, one side of the thin slice in Step Twelve is the target tissue surface of the tooth obtained in Step Eleven, and the other side is the cutting surface.

[0058] Among them, the temperature of the thymol solution is maintained at 4°C.

[0059] Among them, the thickness of the thin slice in Step Twelve is 1 - 2 mm.

[0060] Among them, the prepared polished slices in Step Fifteen are put into absolute ethanol for cleaning and dehydration for 10 - 15 minutes, and then put into xylene for clearing for 10 - 15 minutes.

[0061] Meanwhile, it should be noted that in the present invention, it is not necessary to cut the tooth open first before taking the micro-CT scan. This maintains the integrity of the carious tooth during the micro-CT scan, avoids the problem of reduced X-ray attenuation when photographing partial dental tissue, and can improve the scientificity and accuracy of the research results.

[0062] The present invention allows researchers to first understand the information of tooth lesions on micro-CT images and then selectively select the tissue surfaces to be included in the study, avoiding the blindness of selecting tissue surfaces during visual inspection, thereby improving the sample utilization rate and the success rate of experiments. Thirdly, the present invention cleverly transfers the spatial position relationship set for the tooth in the medical imaging software to the actual tooth by making a 3D printed guide plate, achieving the precise correspondence between the tomographic image and the target tissue surface. At the same time, when making ultra-thin ground sections, the tooth tissue sections are selectively polished in a single direction, effectively protecting the target tissue surface and laying a solid foundation for accurately marking the hierarchical ranges of different carious dentin on the ground sections under the microscope in the subsequent process;

[0063] The method for making tooth ground sections of a specified image tomogram in micro-CT uses 3D modeling technology and 3D printing technology to make a 3D printed guide plate for guiding the cutting direction of dental tissue, achieving the precise transfer from the micro-CT image tomogram to the actual dental tissue surface. By combining the tooth ground section making technology with the 3D printed guide plate and selectively polishing the tooth tissue sections in a single direction, the target tissue surface is effectively protected, and the precise transfer from the micro-CT image tomogram to the ultra-thin tooth ground section is achieved.

[0064] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0065] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0066] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Method for making tooth grinding slices of specified image tomograms in micro-CT, characterized in that: This method comprises the following steps: Step 1: Preserve the freshly extracted tooth in a 0.5% thymol solution, and maintain the temperature of the thymol solution at 4°C; Step 2: Select the target tooth to take micro-CT, and the resolution of the micro-CT taken is below 20um; Step 3: Import the Dicom format data of the micro-CT into medical image processing software, and three-dimensionally reconstruct the 3D tooth model. In this example, the lower left corner tomographic image is selected as an example; Step 4: Draw an analysis cylinder outside the 3D tooth model. The size of the cylinder is based on being able to completely accommodate the tooth model. The distance between each surface of the cylinder and the tooth surface is not less than 4mm to ensure that the 3D printing guide plate has sufficient thickness and strength; Step 5: Perform a Moore subtraction operation on the cylinder and the tooth model to obtain a hollow cylinder containing the tooth structure; Step 6: Observe the tomographic images involving dental caries in the coronal or sagittal image window to determine the tomographic images or tissue surfaces included in the study; Step 7: Cut the layer selected in the previous step in the cross-sectional image window to obtain a hollow cylinder divided into two halves, that is, the 3D printing guide plate; Step 8: Save and output the two respectively as STL files; Step 9: Perform high-precision 3D printing based on the STL file, and select a coated soft rubber material with a softness of 70 to balance the strength and yieldability of the guide plate; Step 10: Select the corresponding 3D guide plate and embed the tooth in it in the corresponding posture to fix the positional relationship of the tooth in three-dimensional space; Step 11: Use a diamond saw blade to cut the tooth along the 3D guide plate under water cooling until the tooth tissue surface is completely parallel to the 3D guide plate. This tooth tissue surface is the image tomogram determined on the micro-CT image in Step 6; Step 12: Remove the tooth from the guide plate, and use a diamond saw blade to cut the tooth into thin slices from the opposite direction under water cooling. One side of the thin slice is the target tooth tissue surface obtained in Step 11, and the other side is the cutting surface; Step 13: Manually polish the slice on an oilstone. When polishing, always keep the cutting surface in contact with the oilstone, and the target tooth tissue surface in contact with the finger, and perform repeated polishing in a single direction; Step 14: Observe the change of the grinding slice. When the grinding slice becomes translucent, measure its thickness, and stop until the thickness reaches about 50um to meet the basic conditions for microscopic observation; Step 15: Put the made grinding slice into anhydrous ethanol for cleaning and dehydration for 10 - 15min, and then put it into xylene for clearing for 10 - 15min; Step 16: Finally, seal the slice with neutral gum for microscopic observation.

2. The method for making tooth grinding slices of specified image tomograms in micro-CT according to claim 1, characterized in that: The thickness of the thin slice in Step 12 is 1 - 2mm.

3. The method for making tooth grinding slices of specified image tomograms in micro-CT according to claim 1, characterized in that: The maintenance time for putting the made grinding slice into anhydrous ethanol for cleaning and dehydration in Step 15 is 10 - 15min, and then put it into xylene for clearing for 10 - 15min.

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