A method for reconstructing tooth edges that have been altered by scanning.

Abstract

To improve quality of scan data of a tooth.SOLUTION: A method according to the present invention includes the steps of: acquiring scan data of a tooth; drawing a closed edge line; deleting scan data of an edge portion of the tooth; arranging data in which a plurality of plates are arranged along the edge line so as to overlap the scan data; creating first and second cross-sectional curves indicating a contour line of the scan data having therebetween a deleted portion in each of a cross section of scan data cut by the plurality of plates of the data; extending the first and second cross-sectional curves in a direction of compensating the scan data in the deleted portion in each of the cross section of the scan data cut by the plurality of plates of the data; and restoring the edge portion of the tooth on the basis of the extended first cross-sectional curve and the extended second cross-sectional curve in each of the cross section of the scan data cut by the plurality of plates of the data.SELECTED DRAWING: Figure 29

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for restoring an edge portion of a tooth that has changed by scanning.

Background Art

[0002] Patent Document 1 discloses a method for estimating and restoring a abutment tooth form that has changed by scanning. The method described in Patent Document 1 deletes a temporary finish line of an edge portion of an abutment tooth, and extends a crown-side temporary finish line and a root-side temporary finish line at the deleted portion. Further, the method described in Patent Document 1 estimates and restores a finish line of an edge portion formed outside the edge portion of the scanned data that has been deleted, based on the extended crown-side temporary finish line and the extended root-side temporary finish line.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the method of Patent Document 1, there is still room for improvement in terms of improving the quality of tooth scan data.

[0005] An object of the present invention is to provide a method and an apparatus capable of improving the quality of tooth scan data.

Means for Solving the Problems

[0006] A method according to an aspect of the present invention is a method for a computer to restore the form of an edge portion of a tooth that has changed by scanning, comprising the step of acquiring scan data of a tooth, The scan data includes the step of drawing a closed edge line indicating the edge of the tooth, The steps include: deleting the scan data of the tooth edge portion based on the edge line in the scan data; A step of superimposing data in which multiple plates are arranged at intervals along the edge line onto the scan data, In each of the cross-sections of the scan data cut by the plurality of plates of the data, a first cross-sectional curve and a second cross-sectional curve showing the outline of the scan data are created with the deleted portion in between. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve and the second cross-sectional curve are extended in a direction that supplements the deleted portion of the scan data. A step of restoring the edge portion of the tooth based on an extended first cross-sectional curve and an extended second cross-sectional curve in each of the cross-sections of the scan data cut by the plurality of plates of the data, Includes.

[0007] An apparatus according to one aspect of the present invention is: A device that restores the morphology of tooth edges that have been altered by scanning, One or more processors, A memory storing instructions that can be executed by the aforementioned one or more processors, It has, The aforementioned instruction is, Steps to obtain dental scan data, The scan data includes the step of drawing a closed edge line indicating the edge of the tooth, The steps include: deleting the scan data of the tooth edge portion based on the edge line in the scan data; A step of superimposing data in which multiple plates are arranged at intervals along the edge line onto the scan data, In each of the cross-sections of the scan data cut by the plurality of plates of the data, a first cross-sectional curve and a second cross-sectional curve showing the outline of the scan data are created with the deleted portion in between. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve and the second cross-sectional curve are extended in a direction that supplements the deleted portion of the scan data. A step of restoring the edge portion of the tooth based on an extended first cross-sectional curve and an extended second cross-sectional curve in each of the cross-sections of the scan data cut by the plurality of plates of the data, Includes. [Effects of the Invention]

[0008] According to the method and apparatus of the present invention, the quality of dental scan data can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] Flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 1 of the present invention [Figure 2] A flowchart illustrating the process of restoring the tooth edge based on the extended first cross-sectional curve and the extended second cross-sectional curve. [Figure 3A] A schematic diagram showing an example of a real tooth. [Figure 3B] A schematic diagram showing an example of scan data of an abutment tooth before restoration. [Figure 4] A schematic diagram showing the process of removing the tooth edges from scanned data. [Figure 5] Schematic diagram showing the process of extracting boundary lines. [Figure 6A] Plan view showing an example of the first data set with multiple plates arranged radially. [Figure 6B] Side view showing an example of the first data set with multiple plates arranged radially. [Figure 7A]Schematic diagram showing the step of superimposing and arranging the first data on the scan data [Figure 7B] Schematic diagram showing the step of superimposing and arranging the first data on the scan data [Figure 8] Schematic diagram showing the step of creating the first cross-sectional curve and the second cross-sectional curve [Figure 9] Schematic diagram showing the step of extending the first cross-sectional curve and the second cross-sectional curve [Figure 10] Schematic diagram showing the intersection line [Figure 11] Schematic diagram showing the restored edge portion based on the boundary line and the intersection line [Figure 12] Schematic diagram showing an example of the scan data of the abutment tooth after restoration [Figure 13A] Schematic diagram showing an example of the edge portion of an actual tooth [Figure 13B] Schematic diagram showing an example of the edge portion of the tooth before restoration [Figure 13C] Schematic diagram explaining the step of deleting the edge portion of the tooth [Figure 13D] Schematic diagram explaining the step of extracting the boundary line [Figure 13E] Schematic diagram explaining the step of creating the first cross-sectional curve and the second cross-sectional curve [Figure 13F] Schematic diagram explaining the step of extending the first cross-sectional curve and the second cross-sectional curve [Figure 13G] Schematic diagram explaining the step of calculating the intersection point of the first cross-sectional curve and the second cross-sectional curve [Figure 13H] Schematic diagram explaining the step of restoring the edge portion of the tooth [Figure 13I] Schematic diagram showing an example of the edge portion of the tooth after restoration [Figure 14] Schematic diagram for explaining the edge portion of the tooth before and after restoration [Figure 15] Schematic block diagram showing the configuration of an apparatus for restoring the edge portion of a tooth changed by scanning according to Embodiment 1 of the present invention [Figure 16A] Schematic diagram showing an example of the scan data of a cavity-forming tooth before restoration [Figure 16B]A schematic diagram showing an example of scan data of a tooth with a cavity prepared after restoration. [Figure 17A] A schematic diagram showing an example of scan data of a tooth with a retention groove before restoration. [Figure 17B] A schematic diagram showing an example of scan data of a tooth with a retention groove after restoration. [Figure 18A] A schematic diagram showing an example of scan data of the dentition before restoration. [Figure 18B] Schematic enlargement of the Z1 portion of the scan data shown in Figure 18A. [Figure 18C] A schematic diagram showing an example of scan data of the restored dentition. [Figure 18D] Schematic enlargement of the Z2 portion of the scan data shown in Figure 18C. [Figure 18E] Schematic cross-sectional view taken along line AA, shown in Figure 18D. [Figure 18F] Schematic enlarged view of section Z3 shown in Figure 18E [Figure 19] Flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 2 of the present invention [Figure 20] A flowchart illustrating the process of restoring the tooth edge based on the extended first cross-sectional curve, extended second cross-sectional curve, extended third cross-sectional curve, and extended fourth cross-sectional curve. [Figure 21] A schematic diagram showing an example of scan data of a tooth with a cavity prepared before restoration. [Figure 22] A schematic diagram showing the process of overlaying the first data onto the scanned data. [Figure 23] Perspective view showing an example of the second data set with multiple plates arranged. [Figure 24] A schematic diagram showing the process of overlaying the second data onto the scanned data. [Figure 25] A schematic diagram showing the process of creating the third cross-sectional curve and the extended fourth cross-sectional curve. [Figure 26A] Flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 3 of the present invention [Figure 26B]Flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 3 of the present invention [Figure 27] A flowchart illustrating the process of restoring the tooth edge based on the extended first cross-sectional curve, extended second cross-sectional curve, extended third cross-sectional curve, extended fourth cross-sectional curve, extended fifth cross-sectional curve, and extended sixth cross-sectional curve. [Figure 28] A schematic diagram showing the process of overlaying the third data onto the scanned data. [Figure 29] Flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 4 of the present invention [Figure 30A] A schematic diagram showing an example of scan data of the tooth edge before restoration. [Figure 30B] A schematic diagram illustrating the process of drawing tooth edge lines. [Figure 30C] A schematic diagram illustrating the process of removing the edges of teeth. [Figure 30D] A schematic diagram showing an example of the fourth data set with multiple plates arranged. [Figure 30E] A schematic diagram showing the process of overlaying the fourth data onto the scanned data. [Figure 31] A photograph taken from the buccal side showing the coping fabricated in Comparative Example 1 attached to the abutment tooth model. [Figure 32] A photograph taken from the buccal side showing the coping fabricated in Example 1 attached to the abutment tooth model. [Figure 33] A photograph taken from the lingual side showing the coping fabricated in Comparative Example 1 attached to the abutment tooth model. [Figure 34] A photograph taken from the lingual side showing the coping fabricated in Example 1 attached to the abutment tooth model. [Modes for carrying out the invention]

[0010] (Background leading to the present invention) Patent Document 1 discloses a method for estimating and reconstructing the shape near the finish line and the finish line itself, which are originally present in an abutment tooth or abutment tooth model, from scan data obtained by scanning the abutment tooth or abutment tooth model.

[0011] However, while the method described in Patent Document 1 can be applied to the estimated reconstruction of the edge portion of an abutment tooth or abutment tooth model, it is not suitable for the estimated reconstruction of the edge portion of teeth with complex shapes. For example, even in teeth with cavity preparation or retention grooves, the margins of the cavity or retention groove are rounded off by scanning compared to their actual shape. The method described in Patent Document 1 has the problem that it is difficult to reconstruct scanned data of complex edge portions, such as the margins of a cavity or retention groove, to a form that is closer to the actual object.

[0012] Furthermore, the method described in Patent Document 1 has the problem that the processing time for estimated restoration tends to be long, making it impossible to restore the morphology of the tooth edge in a short time.

[0013] Therefore, in order to solve these problems, the present inventors have arrived at the following invention.

[0014] The present invention will now be described with reference to the drawings. In all the following drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] (Embodiment 1) [How to restore tooth edges that have been altered by scanning] Figure 1 is a flowchart of a method for restoring the edge portion of a tooth altered by scanning, according to Embodiment 1 of the present invention. Figure 2 is a flowchart illustrating the process of restoring the edge portion of a tooth based on an extended first cross-sectional curve and an extended second cross-sectional curve. The steps shown in Figures 1 and 2 are performed by a computer. Figures 3A-12 are schematic diagrams illustrating each step shown in Figures 1 and 2. Embodiment 1 describes an example of restoring the edge portion of an abutment tooth.

[0016] As shown in Figure 1, step ST1 involves acquiring scan data of the teeth. For example, in step ST1, the teeth are scanned using a scanning device, and scan data of the teeth is acquired. For example, the scanning device can be an intraoral scanner that scans the inside of the patient's mouth, or a desktop scanner that scans a model of teeth. Note that scanning teeth includes scanning actual teeth or scanning a model of teeth.

[0017] For example, tooth scan data may be obtained by directly scanning the patient's oral cavity with an intraoral scanner. Alternatively, in the case of abutment tooth models, tooth scan data may be obtained by placing the abutment tooth model on a stage and scanning the abutment tooth model with a desktop scanner. Or, tooth scan data may be obtained by scanning the oral cavity from outside the patient's mouth using an intraoral scanner.

[0018] Alternatively, the dental scan data may be obtained by receiving it from an external device using a communication device.

[0019] The scan data obtained in step ST1 is a collection of points, containing positional information for each point. Scan data is often output in various formats, such as point cloud data, STL data which includes information on the front and back of faces and normal vectors of faces formed by triangles composed of three adjacent points, wireframe data which consists of triangles formed by connecting adjacent points, or polygon data which has faces drawn on each triangle of the wireframe. In dentistry, STL data is the most commonly used format and is becoming increasingly popular as a common data format with high compatibility across different manufacturers.

[0020] Figure 3A is a schematic diagram showing an example of a real tooth. Figure 3B is a schematic diagram showing an example of scan data of an abutment tooth before restoration. Figure 3B is scan data 10 obtained by scanning the real tooth 100 shown in Figure 3A with a scanning device. As shown in Figures 3A and 3B, in the scan data 10, the edge portion 11 is rounder compared to the edge portion 101 of the real tooth 100.

[0021] Returning to Figure 1, in step ST2, the tooth edge portion 11 is deleted from the scan data 10. For example, in step ST2, the tooth edge portion 11 is deleted based on information entered by the user. Specifically, the user inputs the area of ​​the edge portion 11 through the input interface. Based on the information entered by the user, the edge portion 11 is identified and deleted from the scan data 10.

[0022] Alternatively, in step ST2, edge portions 11 in the scan data 10 may be automatically detected and the detected edge portions 11 may be deleted. For example, the edge portions 11 may be detected based on the curvature or change in curvature of the scan data 10.

[0023] Figure 4 is a schematic diagram showing the process of removing the tooth edge portion from scanned data. As shown in Figure 4, in step ST2, the edge portion 11 of the scanned data 10 is removed. Specifically, in the scanned data 10, the edge portion 11 is removed, and the removed portion 12 and the remaining portion 13 are formed. In the example shown in Figure 4, since the edge portion 11 is formed in an annular shape, the removed portion 12 has an annular shape.

[0024] Returning to Figure 1, in step ST3, the boundary line surrounding the deleted portion 12 is extracted from the scan data 10. For example, in step ST3, the boundary line is extracted by detecting the boundary between the deleted portion 12 and the remaining portion 13 in the scan data 10.

[0025] Figure 5 is a schematic diagram showing the process of extracting boundary lines. As shown in Figure 5, in step ST3, boundary line BL1 surrounding the deleted portion 12 is extracted from the scan data 10. Boundary line BL1 is the line that defines the deleted portion 12. Boundary line BL1 indicates the boundary between the deleted portion 12 and the remaining portion 13 in the outer shape of the tooth, i.e., the contour portion.

[0026] In the scan data 10 of the abutment tooth, the deleted portion 12 has a ring shape, so the boundary line BL1 includes a first boundary line BL11 and a second boundary line BL12. The first boundary line BL11 and the second boundary line BL12 are formed with the deleted portion 12 in between.

[0027] The first boundary line BL11 is the line that defines the inner boundary of the deleted portion 12, and the second boundary line BL12 is the line that defines the outer boundary of the deleted portion 12. In other words, the first boundary line BL11 is the line that is formed on the coronal side of the deleted portion 12, and the second boundary line BL12 is the line that is formed on the root side of the deleted portion 12 compared to the first boundary line BL11.

[0028] Furthermore, if the scan data 10 is in STL format, the extraction of boundary line BL1 may be performed after converting it to polysurface data. Converting to polysurface data makes it easier to extract boundary line BL1.

[0029] Returning to Figure 1, in step ST4, the first data, in which multiple plates are arranged radially, is superimposed on the scan data 10.

[0030] Figures 6A and 6B show an example of a first data set in which multiple plates are arranged radially. Figure 6A is a plan view of the first data set, and Figure 6B is a side view of the first data set. As shown in Figures 6A and 6B, the first data set 20 includes multiple plates 21. The multiple plates 21 are arranged radially. The multiple plates 21 intersect at the central axis CX1 of the first data set 20 and are arranged at equal intervals. The multiple plates 21 have the same shape and size. Each of the multiple plates 21 has a rectangular shape.

[0031] The first data 20 is used to cut the scan data 10 through each of the multiple plates 21 and obtain cross-sectional data of the scan data 10. Based on the cross-sectional data of the scan data 10 obtained using the first data 20, the first and second cross-sectional curves described later are created.

[0032] For example, the number of plates 21 is between 60 and 3500. Preferably, the number of plates 21 is between 90 and 600. This allows the tooth edge portion 11 to be restored to be closer to the real thing. The spacing between the plates 21 is between 1 μm and 400 μm. The number of plates 21 may be predetermined for each tooth shape, or it may be set by user input.

[0033] As shown in Figure 6A, the first data 20 has a circular shape in plan view. As shown in Figure 6B, the first data 20 has a rectangular shape in side view. The shape and dimensions of the first data 20 are designed so that it can be superimposed on the entire scan data 10.

[0034] Figures 7A and 7B are schematic diagrams showing the process of overlaying the first data onto the scan data. Figure 7A shows a top view of the process of overlaying the first data onto the scan data, and Figure 7B shows a side view of the process. As shown in Figures 7A and 7B, in step ST4, the first data 20 is overlaid onto the scan data 10 so as to encompass the entire scan data 10. For example, in step ST4, the central axis CX1 of the first data 20 is positioned along the tooth axis direction of the tooth in the scan data 10. Also, when viewing the scan data 10 in plan view, that is, from the direction from the crown to the root of the tooth, the central axis CX1 of the first data 20 is positioned in the center of the tooth in the scan data 10.

[0035] Returning to Figure 1, in step ST5, in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20, a first cross-sectional curve and a second cross-sectional curve are created that show the outline of the scan data 10, with the deleted portion 12 in between.

[0036] The first data 20 is positioned to penetrate the scan data 10. Therefore, the scan data 10 can be cut by the multiple plates 21 of the first data 20, and cross-sectional data of the scan data 10 can be obtained.

[0037] Figure 8 is a schematic diagram showing the process of creating the first and second cross-sectional curves. As shown in Figure 8, in step ST5, the outline lines of the teeth at each cross-section cut by the multiple plates 21 are extracted from the scan data 10, and the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are created based on the outline lines. This obtains the cross-sectional curve data 30 of the scan data 10. The cross-sectional curve data 30 is formed by the first cross-sectional curve DL1 and the second cross-sectional curve DL2 created at each cross-section.

[0038] The tooth outline line is a line that shows the contour of the tooth in the scan data 10. In the scan data 10, the deleted portion 12 does not have an outline line. Therefore, no cross-sectional curve is created for the deleted portion 12. Thus, in the cross-section of the scan data 10, the deleted portion 12 is sandwiched between the first cross-sectional curve DL1 and the second cross-sectional curve DL2.

[0039] In the example shown in Figure 8, the first cross-sectional curve DL1 is the line created on the crown side of the deleted portion 12, and the second cross-sectional curve DL2 is the line created on the root side of the deleted portion 12.

[0040] Returning to Figure 1, in step ST6, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are extended in the direction that compensates for the deleted portion 12 of the scan data 10.

[0041] Figure 9 is a schematic diagram showing the process of extending the first and second cross-sectional curves. As shown in Figure 9, in step ST6, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are extended in the direction of supplementing the deleted portion 12 of the scan data 10 in the cross-sectional curve data 30 of the scan data 10.

[0042] For example, the first section curve DL1 is extended while maintaining the curvature or change in curvature of the end of the first section curve DL1 that is connected to the deleted portion 12. The second section curve DL2 is extended while maintaining the curvature or change in curvature of the end of the second section curve DL2 that is connected to the deleted portion 12. For example, the end of the first section curve DL1 is the end located on the side of the deleted portion 12, where the first section curve DL1 intersects with the first boundary line BL11. The end of the second section curve DL2 is the end located on the side of the deleted portion 12, where the second section curve DL2 intersects with the second boundary line BL12.

[0043] For example, the first cross-sectional curve DL1 is extended by 0.5 mm or more and 1.0 mm or less from the end of the first cross-sectional curve DL1. Preferably, the first cross-sectional curve DL1 is extended by 0.64 mm from the end of the first cross-sectional curve DL1. The second cross-sectional curve DL2 is extended by 0.5 mm or more and 1.0 mm or less from the end of the second cross-sectional curve DL2. Preferably, the second cross-sectional curve DL2 is extended by 0.64 mm from the end of the second cross-sectional curve DL2.

[0044] Returning to Figure 1, in step ST7, the tooth edge portion 11 is restored based on the extended first cross-sectional curve DL1 and the extended second cross-sectional curve DL2. Step ST7 will be explained using Figure 2.

[0045] As shown in Figure 2, in step ST11, the intersection points where the extended first cross-sectional curve DL1 and the extended second cross-sectional curve DL2 intersect are calculated for each cross-section of the scan data 10 cut by the multiple plates 21 of the first data 20.

[0046] In step ST6, the extended first section curve DL1 and the extended second section curve DL2 intersect each other in the deleted portion 12. In step ST11, the intersection points of the extended first section curve DL1 and the extended second section curve DL2 are calculated for each section.

[0047] In step ST12, the calculated intersection points are connected to create an intersection line. In step ST12, the intersection points calculated in each cross section are connected in three dimensions to create an intersection line.

[0048] Figure 10 is a schematic diagram showing the intersection line. As shown in Figure 10, a closed intersection line CL1 is created by connecting the intersection points calculated in each cross-section in three dimensions.

[0049] Returning to Figure 2, step ST13 restores the tooth edge portion 11 based on the intersection line CL1. Specifically, step ST13 includes step ST14, which creates shape data from the boundary line BL1 to the intersection line CL1.

[0050] Step ST14 will be explained using Figure 11. Figure 11 is a schematic diagram showing the edge portion restored based on the boundary line and the intersection line. As shown in Figure 11, in step ST14, shape data is created from the boundary line BL1 to the intersection line CL1. Specifically, shape data is created from the first boundary line BL11 to the intersection line CL1, and shape data is created from the second boundary line BL12 to the intersection line CL1. This makes it possible to restore the edge portion 14 to the deleted portion 12.

[0051] For example, when creating shape data from boundary line BL1 to intersection line CL1, shape data may be created that fits through a contour curve that defines the shape from boundary line BL1 to intersection line CL1. Alternatively, when creating shape data from boundary line BL1 to intersection line CL1, shape data may be created in each cross section along an extended first cross section curve DL1 and an extended second cross section curve DL2. Alternatively, shape data may be created in each cross section such that the distance between boundary line BL1 and intersection line CL1 is minimized. Note that the creation of shape data is not limited to these methods and may be performed in any way that allows shape data to be created that closely resembles the actual edge portion 101.

[0052] Figure 12 is a schematic diagram showing an example of scan data of an abutment tooth after restoration. As shown in Figure 12, the edge portion 14 of the restored scan data 10 has a sharper shape compared to the edge portion 11 before restoration, resulting in a form that is closer to the actual tooth.

[0053] The restored edge portion 14 can be combined with the deleted portion 12 of the scan data 10 to obtain scan data 10 having the repaired edge portion 14.

[0054] If the restored edge portion 14 is polysurface data, the restored edge portion 14 may be converted to mesh data, then matched with the deleted portion 12 of the scan data 10, and then joined together.

[0055] Furthermore, Figures 13A to 13I will be used to explain the restoration of the tooth edges. Figures 13A to 13I are schematic diagrams showing a series of steps for restoring the tooth edges. Figures 13A to 13I are two-dimensional images illustrating the series of steps by which the tooth edges, which have been altered by the scan described above, are restored.

[0056] Figure 13A is a schematic diagram showing an example of the edge portion of a real tooth. Scan data is obtained by scanning the edge portion 101 of the real tooth 100 shown in Figure 13A using a scanning device.

[0057] Figure 13B is a schematic diagram showing scan data of the edge portion of the actual tooth shown in Figure 13A, representing the scan data of the tooth before restoration. As shown in Figure 13B, in the scan data 10 of the tooth before restoration, the edge portion 11 is rounder than the edge portion 101 of the actual tooth 100 shown in Figure 13A.

[0058] Figure 13C is a schematic diagram illustrating the process of removing edge portions from scan data. As shown in Figure 13C, the edge portions 11 of the scan data 10 are removed. In the scan data 10, a portion 12 is provided where the scan data of the edge portions 11 has been removed.

[0059] Figure 13D is a schematic diagram illustrating the process of extracting boundary lines. As shown in Figure 13D, boundary line BL1 is extracted by detecting the boundary between the deleted portion 12 and the remaining portion 13 in the scanned data 10. Specifically, a first boundary line BL11 and a second boundary line BL12 are extracted with the deleted portion 12 in between. Note that boundary line BL1 extends in the direction of the paper.

[0060] Figure 13E is a schematic diagram illustrating the process of creating the first and second cross-sectional curves. In Figure 13E, by placing the first data 20 into the scan data 10, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are created in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20. Specifically, in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20, the first cross-sectional curve DL1 and the second cross-sectional curve DL2, which show the outline of the scan data 10, are created with the deleted portion 12 in between. The outline of the scan data 10 is the contour line of the remaining portion 13 in each cross-section.

[0061] Figure 13F is a schematic diagram illustrating the process of extending the first and second cross-sectional curves. As shown in Figure 13F, in the deleted portion 12, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are extended in a direction that compensates for the scan data 10 of the deleted portion 12.

[0062] For example, in each cross-section of the scan data 10 cut by multiple plates 21 of the first data 20, the first cross-sectional curve DL1 is extended while maintaining the curvature or rate of change of curvature of the first cross-sectional curve DL1 at the point where the first cross-sectional curve DL1 intersects with the first boundary line BL11. Also, in each cross-section of the scan data 10 cut by multiple plates 21 of the first data 20, the second cross-sectional curve DL2 is extended while maintaining the curvature or rate of change of curvature of the second cross-sectional curve DL2 at the point where the second cross-sectional curve DL2 intersects with the second boundary line BL12.

[0063] Figure 13G is a schematic diagram illustrating the process of calculating the intersection points of the first and second cross-sectional curves. As shown in Figure 13G, at each cross-section, the intersection point P1 where the extended first cross-sectional curve DL1 and the extended second cross-sectional curve DL2 intersect is calculated.

[0064] The intersection points P1 calculated in each cross-section are connected in three dimensions to create the intersection line CL1. The intersection line CL1 corresponds to the restored edge.

[0065] Figure 13H is a schematic diagram illustrating the process of restoring the edge portion of a tooth. As shown in Figure 13H, the edge portion 11 is restored based on the intersection line CL1. Specifically, the restored edge portion 14 is formed on the deleted portion 12 based on the boundary line BL1 and the intersection line CL1. The restored edge portion 14 is obtained by creating shape data from the boundary line BL1 to the intersection line CL1. For example, in each cross section, the restored edge portion 14 is created on the deleted portion 12 by creating shape data from the boundary line BL1 to the intersection line CL1 along the extended first cross section curve DL1 and the extended second cross section curve DL2.

[0066] Figure 13I is a schematic diagram showing an example of a tooth edge after restoration. As shown in Figure 13I, the restored edge portion 14 is placed in the area 12 that was deleted in the scan data 10 and combined with the scan data 10.

[0067] Figure 14 is a schematic diagram illustrating the tooth edge before and after restoration. In Figure 14, the dashed line indicated by reference numeral 11 represents the scanned edge before restoration, and the solid line indicated by reference numeral 14 represents the restored edge 14. As shown in Figure 14, the restored scan data 10 has a sharper edge 14 that is closer to the actual shape than the edge 11 before restoration.

[0068] [Restoration device] Figure 15 is a schematic block diagram showing the configuration of a device for restoring tooth edge portions altered by scanning, according to Embodiment 1 of the present invention.

[0069] As shown in Figure 15, the restoration device 50 is a device that performs the method described above, acquires the scan data 10 before restoration, and outputs the restored scan data 10 with the edge portion 11 restored. The restoration device 50 is, for example, a computer.

[0070] For example, the scan data 10 before restoration is acquired by a scanning device and transmitted to the restoration device 50. The scan data 10 after restoration is transmitted to a fabrication device or the like that makes the prosthesis. The restoration device 50 may also create design data for fabricating the prosthesis based on the scan data 10 after restoration. In this case, the restoration device outputs the design data for the prosthesis.

[0071] The restoration device 50 comprises one or more processors 51, memory 52, and a communication unit 53.

[0072] The processor 51 is, for example, a central processing unit (CPU), a microprocessor, or another processing unit capable of executing computer executable instructions. The processor 51 is capable of executing instructions stored in memory 52.

[0073] Memory 52 stores data from the recovery device 50. Memory 52 includes, for example, a computer recording medium, and includes RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, DVD or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any medium that can be used to store desired information and that the recovery device 50 can access.

[0074] Memory 52 stores a program for executing the method described above. Memory 52 may also store a program for creating design data for the prosthetic device.

[0075] The communication unit 53 communicates with an external device. The communication unit 53 includes a circuit that communicates with the external device in accordance with a predetermined communication standard. The predetermined communication standard includes, for example, LAN, Wi-Fi (registered trademark), Bluetooth (registered trademark), USB, HDMI (registered trademark), CAN (controller area network), and SPI (Serial Peripheral Interface).

[0076] The communication unit 53 receives scan data from the scanning device, for example, via a network. The communication unit 53 also transmits the scan data 10 of the repaired prosthetic device to a fabrication device, etc., via a network, for example.

[0077] [effect] The method for restoring tooth edge portions altered by scanning according to Embodiment 1 of the present invention can achieve the following effects.

[0078] The first embodiment of the present invention is a method for restoring the morphology of a tooth edge portion altered by scanning using a computer, and includes steps ST1 to ST7 performed by a computer. Step ST1 is to acquire scan data 10 of a tooth. Step ST2 is to delete the scan data of the tooth edge portion 11 in the scan data 10. Step ST3 is to extract a boundary line BL1 surrounding the deleted portion 12 in the scan data 10. Step ST4 is to place first data 20, in which a plurality of plates 21 are arranged radially, on top of the scan data 10. Step ST5 is to create first cross-sectional curve DL1 and second cross-sectional curve DL2 that show the outline line of the scan data 10, with the deleted portion 12 in between, in each of the cross-sections of the scan data 10 cut by the plurality of plates 21 of the first data 20. Step ST6 is to extend the first cross-sectional curve DL1 and second cross-sectional curve DL2 in the direction of supplementing the scan data of the deleted portion 12 in each of the cross-sections of the scan data 10 cut by the plurality of plates 21 of the first data 20. Step ST7 restores the tooth edge portion 11 based on the extended first cross-sectional curve DL1 and the extended second cross-sectional curve DL2 in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20.

[0079] This configuration improves the quality of the tooth scan data 10. Specifically, it allows for the restoration of edges that have been rounded by scanning to a form closer to the real thing. Furthermore, the method of Embodiment 1 can be applied to various tooth edges. For example, even edges with complex shapes, such as the margin shape of a cavity or retention groove, or dentition data, can be restored to a form closer to the real thing.

[0080] Furthermore, according to the method of Embodiment 1, the edge portion can be restored in a short time. For example, if the edge portion of an abutment tooth is to be restored, the edge portion can be restored within 10 minutes.

[0081] Step ST7 for restoring the tooth edge portion 11 includes step ST11 for calculating intersections, step ST12 for creating intersection lines, and step ST13 for restoring the edge portion 11. Step ST11 calculates the intersection point P1 where the extended first cross section curve DL1 and the extended second cross section curve DL2 intersect in each cross section of the scan data 10 cut by multiple plates 21 of the first data 20. Step ST12 connects the calculated intersection points P1 to create an intersection line CL1. Step ST13 restores the tooth edge portion 11 based on the intersection line. With this configuration, the edge portion 11 can be restored to a form closer to the real thing, and the quality of the scan data 10 can be further improved.

[0082] Step ST13, which restores the edge portion 11, includes step ST14, which creates shape data from the boundary line BL1 to the intersection line CL1. With this configuration, the edge portion 11 can be restored to a form closer to the actual object, and the quality of the scan data 10 can be further improved. In addition, the edge portion 11 can be restored in a shorter time.

[0083] Step ST6 for extending the first cross-sectional curve DL1 and the second cross-sectional curve DL2 includes the steps of extending the first cross-sectional curve and extending the second cross-sectional curve DL2. The step for extending the first cross-sectional curve extends the first cross-sectional curve DL1 while maintaining the curvature or rate of change of curvature of the first cross-sectional curve DL1 at the end of the first cross-sectional curve DL1 in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20. The step for extending the second cross-sectional curve DL2 extends the second cross-sectional curve DL2 while maintaining the curvature or rate of change of curvature of the second cross-sectional curve DL2 at the end of the second cross-sectional curve DL2 in each of the cross-sections of the scan data 10 cut by the multiple plates 21 of the first data 20. With this configuration, the edge portion 11 can be restored to a form closer to the real thing, and the quality of the scan data 10 can be further improved.

[0084] The first data 20 has a central axis CX1 through which multiple plates 21 intersect. Step ST4, which involves superimposing the first data 20 onto the scan data 10, includes the step of positioning the central axis CX1 of the first data 20 along the tooth axis direction of the tooth. With this configuration, the first cross-sectional curve DL1 and the second cross-sectional curve DL2, which show the outline of the scan data 10, can be created with high accuracy. As a result, the edge portion 11 can be restored to a shape closer to the real thing, and the quality of the scan data 10 can be further improved.

[0085] The step of positioning the central axis CX1 of the first data 20 along the tooth axis direction of the tooth includes the step of positioning the central axis CX1 of the first data 20 in the center of the tooth when viewed from the direction from the crown to the root of the tooth. With this configuration, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 can be created with greater accuracy. As a result, the edge portion 11 can be restored to a shape closer to the real thing, and the quality of the scan data 10 can be further improved.

[0086] The number of plates 21 in the first data 20 is between 60 and 3500. Preferably, the number of plates 21 is between 90 and 600. With this configuration, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 can be created with greater accuracy. As a result, the tooth edge portion 11 can be restored to be closer to the real thing, and the quality of the scan data 10 can be further improved.

[0087] In the first data, the multiple plates are arranged at equal intervals. This configuration allows for the creation of the first cross-sectional curve DL1 and the second cross-sectional curve DL2 with greater accuracy. As a result, the tooth edge portion 11 can be restored to be closer to the real thing, and the quality of the scan data 10 can be further improved.

[0088] The recovery device 50 of Embodiment 1 includes one or more processors 51 and a memory 52 that stores instructions executable by one or more processors 51. The instructions include the steps of the method described above. This configuration produces the same effects as the method described above.

[0089] In Embodiment 1, an example was described in which the method includes step ST3 for extracting boundary line BL1, but the method is not limited to this. For example, the method does not include step ST3 for extracting boundary line BL1. In this case, in step ST7, shape data of the deleted portion may be created based on the extended first cross-sectional curve DL1, the extended second cross-sectional curve DL2, and the intersecting line CL1.

[0090] Embodiment 1 described an example in which the multiple plates 21 in the first data 20 have a rectangular shape, but it is not limited to this. The shape of the multiple plates 21 is not limited to a rectangular shape. For example, the shape of the multiple plates 21 may be elliptical or polygonal.

[0091] Embodiment 1 described an example in which multiple plates 21 in the first data 20 are arranged at equal intervals, but it is not limited to this. For example, the intervals between multiple plates 21 may be different.

[0092] Embodiment 1 describes an example in which the tooth edge portion 11 is restored using scan data of an abutment tooth, but the invention is not limited to this. For example, the tooth edge portion 11 may be the abutment tooth cavity, retention groove, or the edge portion (margin portion) of the dentition. Also, the tooth edge portion 11 may be the edge portion 11 of a tooth model.

[0093] Figure 16A is a schematic diagram showing an example of scan data of a cavity-prepared tooth before restoration. Figure 16B is a schematic diagram showing an example of scan data of a cavity-prepared tooth before restoration. In Figures 16A and 16B, the edge portion before restoration is indicated by the symbol "11A", and the edge portion after restoration is indicated by the symbol "14A". In the examples shown in Figures 16A and 16B, the edge portion 11A of the scan data 10A of the cavity-prepared tooth, i.e., the margin of the cavity 15, is restored using this method.

[0094] Comparing the pre-restoration edge portion 11A shown in Figure 16A with the restored edge portion 14A shown in Figure 16B, the restored edge portion 14A has a sharper shape than the pre-restoration edge portion 11A, and has been restored to a form closer to the margin of the actual cavity 15.

[0095] Figure 17A is a schematic diagram showing an example of scan data of a tooth with a retention groove before restoration. Figure 17B is a schematic diagram showing an example of scan data of a tooth with a retention groove after restoration. In Figures 17A and 17B, the edge portion before restoration is indicated by the symbol "11B", and the edge portion after restoration is indicated by the symbol "14B". In the examples shown in Figures 17A and 17B, the edge portion 11B of the scan data 10B of the tooth with a retention groove, i.e., the margin of the retention groove 16, is restored using this method.

[0096] Comparing the edge portion 11B before restoration shown in Figure 17A with the edge portion 14B after restoration shown in Figure 17B, the restored edge portion 14B has a sharper shape than the edge portion 11B before restoration, and has been restored to a form closer to the margin of the actual maintenance groove 16.

[0097] Figure 18A is a schematic diagram showing an example of scan data of the dentition before restoration. Figure 18B is a magnified schematic diagram of the Z1 portion shown in Figure 18. Figure 18C is a schematic diagram showing an example of scan data of the dentition after restoration. Figure 18D is a magnified schematic diagram of the Z2 portion shown in Figure 18C. In Figures 18A-18D, the edge portion before restoration is indicated by the symbol "11C", and the edge portion after restoration is indicated by the symbol "14C". In the example shown in Figures 18A-18D, the edge portion 11C of the abutment tooth of the canine tooth, i.e., the margin of the abutment tooth of the canine tooth, is restored from the scan data 10C of the dentition. Furthermore, when performing this method, the abutment tooth of the canine tooth is separated from the dentition. That is, this method is performed on the portion of the scan data 10C of the dentition where the abutment tooth of the canine tooth is located. This reduces the computational processing and allows the edge portion 11C to be restored in a short time. In the examples shown in Figures 18A-18D, the method is described in which the abutment tooth of the canine tooth is separated from the dentition, but it is not limited to this. For example, the method may be performed without separating the abutment tooth from the dentition. Also, the abutment tooth of the canine tooth is just one example, and the method may be performed on other abutment teeth.

[0098] Comparing the edge portion 11C of the abutment tooth of the canine tooth before restoration, shown in Figures 18A and 18B, with the edge portion 14C of the abutment tooth of the canine tooth after restoration, shown in Figures 18C and 18D, the edge portion 14C after restoration has a sharper shape than the edge portion 11C before restoration, and has been restored to a form close to the actual edge portion of the abutment tooth of the canine tooth, i.e., the margin.

[0099] Figure 18E is a schematic cross-sectional view taken along line AA shown in Figure 18D. Figure 18F is a schematic enlarged view of section Z3 shown in Figure 18E. In Figures 18E and 18F, the edge portion 11C before restoration is shown with a dotted line, and the edge portion 14C after restoration is shown with a solid line. As can be seen from Figures 18E and 18F, the edge portion 14C after restoration has a sharper shape than the edge portion 11C before restoration, and has been restored to a shape close to the edge portion of a real canine abutment tooth, i.e., the margin.

[0100] Thus, according to the method of Embodiment 1, even edge portions with complex shapes can be restored with high accuracy.

[0101] In Embodiment 1, the components of the restoration device 50 may be changed, added, deleted, integrated, or divided. For example, the restoration device 50 does not have to include a communication unit 53. The restoration device 50 may include a scanning device. Alternatively, the restoration device 50 may store a program for designing prosthetic devices in its memory 52.

[0102] Embodiment 1 describes examples of methods and apparatus, but is not limited thereto. The method of Embodiment 1 may be implemented by a program for performing the method, or by a computer-readable recording medium on which the program for performing the method is recorded. For example, the computer-readable medium may include the method of Embodiment 1 as a computer-readable instruction that can be executed by a processor. The computer-readable medium may include various types of volatile and non-volatile recording media, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), electrically programmable read-only memory (PROM), electrically erasable read-only memory (EPROM), flash memory, several other tangible data storage devices, and several combinations thereof.

[0103] The method and apparatus according to Embodiment 1 may be included in a method, apparatus, or system for manufacturing a prosthetic device.

[0104] (Embodiment 2) The method of Embodiment 2 according to the present invention will now be described.

[0105] Embodiment 2 will primarily describe the differences from Embodiment 1. In Embodiment 2, components identical or equivalent to those in Embodiment 1 will be denoted by the same reference numerals. Furthermore, in Embodiment 2, descriptions that overlap with those in Embodiment 1 will be omitted.

[0106] Figure 19 is a flowchart illustrating a method for restoring tooth edge portions altered by scanning according to Embodiment 2 of the present invention. Figure 20 is a flowchart illustrating the process of restoring tooth edge portions based on extended first cross-sectional curves, extended second cross-sectional curves, extended third cross-sectional curves, and extended fourth cross-sectional curves.

[0107] Embodiment 2 differs from Embodiment 1 in that the tooth edge portion 11A is restored using the second data.

[0108] In Embodiment 2, steps ST21 to ST26 shown in Figure 19 are the same as steps ST1 to ST6 in Embodiment 1, and steps ST31, ST34, and ST35 shown in Figure 20 are the same as steps ST11, ST13, and ST14 in Embodiment 1. Therefore, a detailed explanation of these steps will be omitted.

[0109] Furthermore, Embodiment 2 describes an example of restoring the edge portion of the scan data of a cavity-prepared tooth, i.e., the cavity margin.

[0110] As shown in Figure 19, in step ST21, scan data of the cavity-prepared tooth is acquired.

[0111] Figure 21 is a schematic diagram showing an example of scan data of a cavity-prepared tooth before restoration. Figure 21 is a plan view of the cavity-prepared tooth, that is, a view from the direction from the crown to the root. As shown in Figure 21, in the scan data 10A of the cavity-prepared tooth before restoration, the margin of the cavity 15, which is the edge portion 11A, is rounded.

[0112] Returning to Figure 19, in step ST22, the edge portion 11A of the cavity-prepared tooth is removed.

[0113] In step ST23, the boundary line BL1 surrounding the deleted portion in the scan data 10A of the cavity-prepared tooth is extracted.

[0114] In step ST24, the first data 20 is placed on top of the scan data 10A.

[0115] Figure 22 is a schematic diagram showing the process of overlaying the first data onto the scan data. As shown in Figure 22, the first data 20 is overlaid on the scan data 10A such that the central axis CX1 of the first data 20 is aligned with the tooth axis direction of the cavity-prepared tooth.

[0116] Returning to Figure 19, in step ST25, in each of the cross-sections of the scan data 10A cut by the multiple plates 21 of the first data 20, a first cross-sectional curve DL1 and a second cross-sectional curve DL2 are created that show the outline of the scan data 10A, with the deleted portion in between.

[0117] In step ST25, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are extended in the direction of supplementing the scanned data of the deleted portion.

[0118] In step ST26, the second data 22, which consists of multiple plates 23 arranged in a sequence, is placed on top of the scan data 10A.

[0119] Figure 23 is a perspective view showing an example of a second data set in which multiple plates are arranged. As shown in Figure 23, the second data set 22 includes multiple plates 23. The multiple plates 23 are arranged in one direction. The multiple plates 23 are arranged parallel to each other. The multiple plates 23 are arranged at equal intervals in one direction. The one direction is the direction in which the central axis CX2 of the second data set 22 extends.

[0120] The multiple plates 23 have the same shape and size. Each of the multiple plates 23 has a disc shape.

[0121] The second data set 22 is used to cut the scan data 10A through each of the multiple plates 23 and obtain cross-sectional data of the scan data 10A. Based on the cross-sectional data of the scan data 10A obtained using the second data set 22, the third and fourth cross-sectional curves, described later, are created.

[0122] The second data 22 is positioned to penetrate the scan data 10A. Therefore, the scan data 10A can be cut by the multiple plates 23 of the second data 22, and cross-sectional data of the scan data 10A can be obtained.

[0123] Figure 24 is a schematic diagram showing the process of overlaying the second data onto the scan data. As shown in Figure 24, the second data 22 is overlaid on the scan data 10A so that the arrangement direction of the multiple plates 23 intersects with the tooth axis direction of the cavity-forming tooth. In Embodiment 2, the second data 22 is overlaid on the scan data 10A so that the arrangement direction of the multiple plates 23 is perpendicular to the tooth axis direction of the cavity-forming tooth.

[0124] Returning to Figure 19, in step ST27, a third and fourth cross-sectional curve representing the outline of the scan data 10A is created in each of the cross-sections of the scan data 10A cut by the multiple plates 23 of the second data 22, with the deleted portion in between.

[0125] Figure 25 is a schematic diagram showing the process of creating the third cross-sectional curve and the extended fourth cross-sectional curve. Note that Figure 25 shows one side of the cross-sectional curve data 31 of the scan data 10A, and the other side is not shown. As shown in Figure 25, in each cross-section of the scan data 10A cut by the multiple plates 23 of the second data 22, the deleted portion 12 is sandwiched in between, and the third cross-sectional curve DL3 and the fourth cross-sectional curve DL4, which represent the outline of the scan data 10A, are created. The outline of the scan data 10A refers to the contour line of the cavity-prepared tooth.

[0126] In the example shown in Figure 25, the third cross-sectional curve DL3 is created on the crown side of the deleted portion 12A, and the fourth cross-sectional curve DL4 is created on the crown side of the deleted portion 12A.

[0127] Returning to Figure 19, in step ST29, the third cross-sectional curve DL3 and the fourth cross-sectional curve DL4 are extended in the direction of supplementing the scan data 10A of the deleted portion 12A. The method of extending the third cross-sectional curve DL3 and the fourth cross-sectional curve DL4 is the same as the method of extending the first cross-sectional curve DL1 and the second cross-sectional curve DL2.

[0128] In step ST30, the edge portion 11A of the cavity-prepared tooth is restored based on the extended first cross-sectional curve DL1, the extended second cross-sectional curve DL2, the extended third cross-sectional curve DL3, and the extended fourth cross-sectional curve DL4. Step ST30 will be explained using Figure 20.

[0129] As shown in Figure 20, in step ST31, the first intersection point where the extended first cross-sectional curve DL1 and the extended second cross-sectional curve DL2 intersect is calculated for each cross-section of the scan data 10A cut by the multiple plates 21 of the first data 20.

[0130] In step ST32, the second intersection point is calculated where the extended third cross-sectional curve DL3 and the extended fourth cross-sectional curve DL4 intersect in each cross-section of the scan data 10A cut by the multiple plates 23 of the second data 22.

[0131] In step ST29, the extended third section curve DL3 and the extended fourth section curve DL4 intersect each other in the deleted portion 12A. In step ST32, the second intersection point of the extended third section curve DL3 and the extended fourth section curve DL4 is calculated for each section.

[0132] In step ST33, the intersection line CL1 is created based on the calculated first and second intersections. Specifically, the intersection line CL1 is created by three-dimensionally connecting the first and second intersections calculated in each cross section. For example, the intersection line CL1 is created by connecting the points that are closest to each other at the first and second intersections.

[0133] In step ST34, the edge portion 11A of the cavity-prepared tooth is restored based on the intersecting line CL1. Specifically, step ST34 includes step ST35, which creates the edge portion 11A based on the boundary line BL1 and the intersecting line CL1.

[0134] In step ST35, shape data is created from the boundary line BL1 to the intersection line CL1. This allows the edge portion 14A to be restored to the deleted portion 12A.

[0135] [effect] The method of Embodiment 2 of the present invention can achieve the following effects.

[0136] The method of Embodiment 2 according to the present invention restores the edge portion 11A of the scan data 10A of a cavity-prepared tooth using first data 20 and second data 22. Specifically, the method of Embodiment 2 includes steps ST27 to ST29 in addition to those of Embodiment 1. Step ST27 involves placing the second data 22, which has a plurality of plates 23 arranged in it, on top of the scan data 10A. Step ST28 involves creating a third cross-sectional curve DL3 and a fourth cross-sectional curve DL4 that show the outline line of the scan data 10A, with the deleted portion 12A sandwiched in between, at each of the cross-sections of the scan data 10A cut by the plurality of plates 23 of the second data 22. Step ST29 involves extending the third cross-sectional curve DL3 and the fourth cross-sectional curve DL4 in a direction that complements the scan data of the deleted portion 12A at each of the cross-sections of the scan data 10A cut by the plurality of plates 23 of the second data 22. Furthermore, in the method of Embodiment 2, step ST30 for restoring the tooth edge portion restores the edge portion 11A of the cavity-prepared tooth based on the extended first cross-sectional curve DL1, the extended second cross-sectional curve DL2, the extended third cross-sectional curve DL3, and the extended fourth cross-sectional curve DL4.

[0137] This configuration allows for further improvement of the quality of the tooth edges in the scan data 10A. For example, in the scan data 10A of a cavity-prepared tooth, the edges 11A, such as the margins of the cavity 15, can be restored to be closer to the real thing.

[0138] Thus, according to the method of Embodiment 2, the edge portion 11A of a tooth with a complex shape, such as a cavity-prepared tooth, can be restored to be closer to the real thing by using the first data 20 and the second data 22. This makes it possible to create even higher quality scan data 10A.

[0139] Step ST30 includes steps ST31 for calculating a first intersection, ST32 for calculating a second intersection, ST33 for creating an intersection line, and ST34 for restoring the edge portion. Step ST31 calculates a first intersection where an extended first cross section curve DL1 and an extended second cross section curve DL2 intersect in each cross section of the scan data 10A cut by multiple plates 21 of the first data 20. Step ST32 calculates a second intersection where an extended third cross section curve DL3 and an extended fourth cross section curve DL4 intersect in each cross section of the scan data 10A cut by multiple plates 23 of the second data 22. Step ST33 creates an intersection line CL1 based on the calculated first and second intersections. Step ST34 restores the tooth edge portion 11A based on the intersection line CL1. With this configuration, the tooth edge portion 11A, which has a complex shape, can be restored to be closer to the real thing.

[0140] The first data 20 has a central axis CX1 where multiple plates 21 intersect. Step ST24, in which the first data 20 is superimposed on the scan data 10A, includes positioning the first data 20 so that the central axis CX1 is aligned with the tooth axis direction of the tooth. Step ST27, in which the second data 22 is superimposed on the scan data 10A, includes positioning the second data 22 so that the arrangement direction of the multiple plates 23 intersects with the tooth axis direction of the tooth. With this configuration, the intersecting line CL1 indicating the tooth edge can be created to be closer to the actual edge line. As a result, the tooth edge portion 11A with a complex shape can be restored to be closer to the actual object.

[0141] In Embodiment 2, an example was described in which the second data 22 is superimposed on the scan data 10A so that the arrangement direction of the multiple plates 23 intersects with the tooth axis direction of the teeth, but the invention is not limited to this. For example, the second data 22 may be superimposed on the scan data 10A so that the arrangement direction of the multiple plates 23 is aligned with the tooth axis direction of the teeth. Alternatively, the second data 22 may be superimposed on the scan data 10A based on information entered by the user.

[0142] Embodiment 2 describes an example in which the second data 22 is superimposed on the entire scan data 10A, but is not limited to this. For example, the second data 22 may be partially superimposed on the scan data 10.

[0143] Embodiment 2 described an example in which each of the multiple plates 23 in the second data 22 has a disc shape, but is not limited to this. For example, each of the multiple plates 23 only needs to have a plate shape, and may have a rectangular, polygonal, or elliptical shape when viewed from the thickness direction.

[0144] Embodiment 2 described an example in which multiple plates 23 of the second data 22 are arranged in parallel, but is not limited to this. For example, the multiple plates 23 may be arranged in a curved shape.

[0145] In Embodiment 2, an example was described in which multiple plates 23 of the second data 22 are arranged at equal intervals, but the invention is not limited to this. For example, the multiple plates 23 may be arranged at different intervals.

[0146] (Embodiment 3) The method according to Embodiment 3 of the present invention will now be described.

[0147] Embodiment 3 will primarily describe the differences from Embodiment 2. In Embodiment 3, components identical or equivalent to those in Embodiment 2 will be denoted by the same reference numerals. Furthermore, in Embodiment 3, descriptions that overlap with those in Embodiment 2 will be omitted.

[0148] Figures 26A and 26B are flowcharts illustrating a method for restoring tooth edge portions altered by scanning according to Embodiment 3 of the present invention. Figure 27 is a flowchart illustrating the process of restoring tooth edge portions based on extended first cross-sectional curves, extended second cross-sectional curves, extended third cross-sectional curves, extended fourth cross-sectional curves, extended fifth cross-sectional curves, and extended sixth cross-sectional curves.

[0149] Embodiment 3 differs from Embodiment 2 in that it uses third data to reconstruct the tooth edge portion 11A.

[0150] In Embodiment 3, steps ST41 to ST49 shown in Figure 26A are the same as steps ST21 to ST29 in Embodiment 2, and steps ST61, ST62, ST65, and ST66 shown in Figure 27 are the same as steps ST31, ST32, ST34, and ST35 in Embodiment 2. Therefore, a detailed explanation of these steps will be omitted.

[0151] Furthermore, in Embodiment 3, similar to Embodiment 2, an example of restoring the edge portion of the scan data of a cavity-prepared tooth, i.e., the cavity margin, will be described.

[0152] As shown in Figure 26A, steps ST41 to ST49 are carried out. In Embodiment 3, in step ST47, the direction in which the multiple plates 23 of the second data 22 are arranged is referred to as the "first direction".

[0153] As shown in Figure 26B, in step ST50, the third data, in which multiple plates are arranged along the second direction, is superimposed on the scan data 10A. The second direction means a direction different from the first direction. For example, the second direction is a direction that intersects the first direction. In Embodiment 3, the second direction is perpendicular to the first direction. That is, the second direction is a direction along the tooth axis of the cavity-prepared tooth.

[0154] Figure 28 is a schematic diagram showing the process of overlaying the third data onto the scan data. As shown in Figure 28, in step ST50, the third data 24, in which multiple plates 25 are arranged along a second direction different from the first direction in which multiple plates 23 are arranged in the second data 22, is overlaid onto the scan data 10A.

[0155] The third data set 24, like the second data set 22, includes multiple plates 25. The multiple plates 25 are arranged in a second direction. The multiple plates 23 are arranged at equal intervals in the second direction. The second direction is the direction in which the central axis CX3 of the third data set extends.

[0156] In the third data point 24, the central axis CX3 of the third data point 24 is positioned so that it passes through the center of the cavity-prepared tooth in a plan view.

[0157] The multiple plates 25 have the same shape and size. Each of the multiple plates 25 has a disc shape.

[0158] In Embodiment 3, the plurality of plates 25 of the third data 24 are the same as the plurality of plates 23 of the second data 22, except for the arrangement direction.

[0159] The third data set 24 is used to cut the scan data 10A through each of the multiple plates 25 and obtain cross-sectional data of the scan data 10A. Based on the cross-sectional data of the scan data 10A obtained using the third data set 24, the fifth and sixth cross-sectional curves, described later, are created.

[0160] The third data 24 is positioned to penetrate the scan data 10A. Therefore, the scan data 10A can be cut by the multiple plates 25 of the third data 24, and cross-sectional data of the scan data 10A can be obtained.

[0161] Returning to Figure 26B, in step ST51, in each of the cross-sections of the scan data 10A cut by the multiple plates 25 of the third data 24, a fifth and sixth cross-sectional curve are created, showing the outline of the scan data 10A with the deleted portion in between. Step ST51 is similar to step ST48, which creates the third and fourth cross-sectional curves, so a detailed explanation is omitted.

[0162] In step ST52, the fifth and sixth cross-sectional curves are extended in the direction of supplementing the deleted portion of the scan data. Step ST52 is similar to step ST48, which extends the third and fourth cross-sectional curves, so a detailed explanation is omitted.

[0163] In step ST53, the tooth edge is restored based on the extended first cross-sectional curve, extended second cross-sectional curve, extended third cross-sectional curve, extended fourth cross-sectional curve, extended fifth cross-sectional curve, and extended sixth cross-sectional curve. Step ST52 will be explained using Figure 27.

[0164] As shown in Figure 27, in step ST61, a first intersection point is calculated where the extended first cross-sectional curve and the extended second cross-sectional curve intersect in each cross-section of the scan data 10A cut by the multiple plates 21 of the first data 20.

[0165] In step ST62, the second intersection point where the extended third cross-sectional curve and the extended fourth cross-sectional curve intersect is calculated for each cross-section of the scan data 10A cut by the multiple plates 23 of the second data 22.

[0166] In step ST63, the third intersection point is calculated where the extended fifth cross-sectional curve and the extended sixth cross-sectional curve intersect in each cross-section of the scan data 10A cut by the multiple plates 25 of the third data 24. Step ST63 calculates the third intersection point in the same manner as in step ST62.

[0167] In step ST64, the intersection line CL1 is created based on the calculated first, second, and third intersections. Specifically, the first, second, and third intersections calculated in each section are connected in three dimensions to create the intersection line CL1.

[0168] In step ST65, the edge portion 11A of the cavity-prepared tooth is restored based on the intersecting line CL1. Specifically, step ST65 has step ST66, which creates the edge portion 11A based on the boundary line BL1 and the intersecting line CL1.

[0169] In step ST66, shape data is created from the boundary line BL1 to the intersection line CL1. This allows the edge portion to be restored to the deleted portion 12A in the scan data 10A.

[0170] [effect] The method of Embodiment 3 of the present invention can achieve the following effects.

[0171] The method of Embodiment 3 according to the present invention restores the edge portion 11A of the scan data 10A of a cavity-prepared tooth using first data 20, second data 22, and third data 24. Specifically, the method of Embodiment 3 includes steps ST50 to ST52 in addition to those of Embodiment 2. Step ST50 places third data 24, in which a plurality of plates 25 are arranged along a second direction different from the first direction in which a plurality of plates 23 are arranged in second data 22, on top of the scan data 10A. Step ST51 creates a fifth cross-sectional curve and a sixth cross-sectional curve showing the outline line of the scan data 10A, with the deleted portion 12A in between, in each of the cross-sections of the scan data 10A cut by the plurality of plates 25 of third data 24. Step ST52 extends the fifth cross-sectional curve and the sixth cross-sectional curve in a direction that complements the scan data of the deleted portion 12A, in each of the cross-sections of the scan data 10A cut by the plurality of plates 25 of third data 24. Furthermore, in the method of Embodiment 3, step ST53 for restoring the tooth edge portion restores the edge portion 11A of the cavity-prepared tooth based on the extended first cross-sectional curve, extended second cross-sectional curve, extended third cross-sectional curve, extended fourth cross-sectional curve, extended fifth cross-sectional curve, and extended sixth cross-sectional curve.

[0172] This configuration allows for further improvement of the quality of the tooth edges in the scan data 10A. For example, in the scan data 10A of a cavity-prepared tooth, the edges 11A, such as the margins of the cavity 15, can be restored to be closer to the real thing.

[0173] Thus, in Embodiment 3, the edge portion 11A of the scan data 10A of the cavity-prepared tooth can be restored with even greater accuracy by using the first data 20, the second data 22, and the third data 24.

[0174] In Embodiment 3, an example was described in which the plurality of plates 25 of the third data 24 are the same as the plurality of plates 23 of the second data 22, but the invention is not limited to this. For example, the plurality of plates 25 of the third data 24 may be different from the plurality of plates 23 of the second data 22.

[0175] (Embodiment 4) The fourth embodiment of the present invention will now be described.

[0176] Embodiment 4 will primarily describe the differences from Embodiment 1. In Embodiment 4, components identical or equivalent to those in Embodiment 1 will be denoted by the same reference numerals. Furthermore, in Embodiment 4, descriptions that overlap with those in Embodiment 1 will be omitted.

[0177] Figure 29 is a flowchart of a method for restoring tooth edge portions altered by scanning according to Embodiment 4 of the present invention. Figures 30A to 30E are schematic diagrams illustrating the steps of the method for restoring tooth edge portions altered by scanning according to Embodiment 4 of the present invention.

[0178] Embodiment 4 differs from Embodiment 1 in that the tooth edge portion 11D is restored using the fourth data 26.

[0179] In Embodiment 4, steps ST71, ST74, and ST76-ST78 shown in Figure 29 are the same as steps ST1, ST3, and ST5-ST7 in Embodiment 1. Therefore, a detailed explanation of these steps will be omitted.

[0180] Furthermore, Embodiment 4 describes an example of restoring the edge portion of the scan data of a cavity-prepared tooth, i.e., the cavity margin.

[0181] As shown in Figure 29, in step ST71, scan data 10D of the cavity-prepared tooth is acquired.

[0182] Figure 30A is a schematic diagram showing an example of scan data of a cavity-prepared tooth before restoration. As shown in Figure 30A, in the scan data 10D of the cavity-prepared tooth before restoration, the margin of the cavity 15, which is the edge portion 11D, is rounded.

[0183] Returning to Figure 29, in step ST72, closed edge lines indicating the tooth edges are drawn in the scan data 10D.

[0184] Figure 30B is a schematic diagram illustrating the process of drawing tooth edge lines. As shown in Figure 30B, edge lines EL1, which indicate the tooth edge, are drawn in the scan data 10D of the cavity-prepared tooth. Edge line EL1 is a closed line with a start point and an end point connected. For example, edge line EL1 is a curve that follows the edge of the tooth.

[0185] The edge line EL1 is drawn along the edge of the tooth in the scan data 10D. For example, the edge line EL1 may be drawn based on information entered by the user through an input interface. Alternatively, the edge line EL1 may be drawn automatically by detecting edges using an edge detection algorithm and connecting the detected edges.

[0186] Returning to Figure 29, in step ST73, the tooth edge portion 11D is removed based on the edge line EL1 in the scan data 10D.

[0187] Figure 30C is a schematic diagram illustrating the process of removing the tooth edge portion. In Figure 30C, the tooth edge portion 11D is removed in the scan data 10D, and the removed portion 12 is shown. The scan data of the tooth edge portion 11D is removed based on the edge line EL1. For example, in the scan data 10D, scan data within a predetermined range centered on the edge line EL1 is removed. That is, scan data within a predetermined distance from the edge line L1 in the normal direction of the edge line EL1 is removed. Specifically, scan data in a tubular region centered on the edge line EL1 is removed.

[0188] Returning to Figure 29, in step ST74, the boundary line BL1 surrounding the deleted portion 12D in the scan data 10D of the cavity-prepared tooth is extracted.

[0189] In step ST75, the fourth data 26, in which multiple plates 25D are arranged at intervals along the edge line EL1, is superimposed on the scan data 10D.

[0190] Figure 30D is a schematic diagram showing an example of a fourth data set in which multiple plates are arranged. As shown in Figure 30D, the fourth data set 26 is data in which multiple plates 25D are arranged along the edge line EL1. The multiple plates 25D are arranged so as to coincide with the normal direction of the edge line EL1. In other words, each of the multiple plates 25D is arranged perpendicular to the edge line EL1.

[0191] For example, the multiple plates 25D have a disc shape and are arranged at equal intervals. The outer diameter of the plates 25D is larger than the diameter of the portion 12D removed in step ST73. For example, the number of multiple plates 25D is 30 to 3500. Preferably, the number of multiple plates 25D is 200 to 500. This makes it possible to restore the tooth edge portion 11D to be closer to the real thing. The spacing between the multiple plates 25D is 10 μm to 400 μm. Preferably, the spacing between the multiple plates 25D is 40 μm to 100 μm.

[0192] The number of plates 25D may be automatically set according to the length of the edge line EL1. For example, the start and end points of the edge line EL1 may be calculated, and the plates 25D may be arranged between the start and end points at predetermined intervals. In this case, the number of plates 25D will be automatically set based on the length of the edge line EL1 and the intervals between the plates 25D.

[0193] That is, step ST75 may include obtaining the length of the edge line EL1 and the spacing between the multiple boards 25D, and determining the number of multiple boards 25D based on the length of the edge line EL1 and the spacing between the multiple boards 25D.

[0194] Figure 30E is a schematic diagram showing the process of overlaying the fourth data onto the scan data. As shown in Figure 30E, the fourth data 26, which includes multiple plates 25D, is placed in the area 12D that was deleted from the scan data 10D. Since the outer diameter of the multiple plates 25D is larger than the deleted area 12D, the multiple plates 25D overlap with the remaining portion in the scan data 10D. As a result, a cross-section of the scan data 10D is obtained in the area where the multiple plates 25D overlap.

[0195] Returning to Figure 29, in step ST76, in each of the cross-sections of the scan data 10D cut by the multiple plates 25D of the fourth data 26, a first cross-sectional curve DL1 and a second cross-sectional curve DL2 are created that show the outline of the scan data 10D, with the deleted portion in between.

[0196] In step ST77, the first cross-sectional curve DL1 and the second cross-sectional curve DL2 are extended in a direction that compensates for the deleted scan data of section 12D.

[0197] In step ST78, the tooth edge is restored based on the extended first cross-sectional curve and the extended second cross-sectional curve DL2.

[0198] Steps ST76 to ST78 are the same as steps ST5 to ST7 in Embodiment 1, and the processes performed in steps ST76 to ST78 are the same as those described in Figures 13A to 13I of Embodiment 1.

[0199] [effect] The method of Embodiment 4 of the present invention can achieve the following effects.

[0200] The method of Embodiment 4 according to the present invention restores the edge portion 11D of tooth scan data 10D using fourth data 26. Specifically, the method of Embodiment 4 includes steps ST71 to ST78. Step ST71 acquires tooth scan data 10D. Step ST72 draws a closed edge line EL1 indicating the edge of the tooth in the scan data 10D. Step ST73 deletes the scan data of the tooth edge portion 11D based on the edge line EL1 in the scan data 10D. Step ST74 places fourth data 26, in which a plurality of plates 25D are arranged at intervals along the edge line EL1, on top of the scan data 10D. Step ST75 creates a first cross-sectional curve DL1 and a second cross-sectional curve DL2 indicating the outline line of the scan data 10D, with the deleted portion 12D in between, in each of the cross-sections of the scan data 10D cut by the plurality of plates 25D of fourth data 26. Step ST76 extends the first cross section curve DL1 and the second cross section curve DL2 in each of the cross sections of the scan data cut by the multiple plates 25D of the fourth data 26 in a direction that complements the deleted portion 12D of the scan data. Step ST77 restores the tooth edge portion based on the extended first cross section curve DL1 and the extended second cross section curve DL2 in each of the cross sections of the scan data cut by the multiple plates 25D of the fourth data 26.

[0201] This configuration allows for further improvement of the quality of tooth scan data. According to the method of Embodiment 4, the edge portions of scan data of teeth with large height differences and complex shapes, such as cavities, can be restored to an edge shape close to that of the actual tooth. For example, scan data of tooth edges that have been rounded during scanning can be restored to a sharp edge shape close to that of the actual tooth.

[0202] Furthermore, according to the method of Embodiment 4, a closed edge line EL1 indicating the edge of the tooth is drawn, and multiple plates 25D are placed along the edge line EL1, thus reducing processing compared to Embodiment 1. As a result, the method of Embodiment 4 can restore scan data of the edge portion in a shorter time compared to the method of Embodiment 1. In particular, to restore scan data of the edge portion of teeth with complex shapes, such as cavities, with higher accuracy, a method is adopted in which the first data and second data, which include multiple plates arranged radially, are placed in different directions, as in Embodiment 2. In Embodiment 4, since multiple plates are placed along the edge line EL1, the edge portion can be restored in the same way for all cases.

[0203] Step ST74, which involves overlaying the fourth data 26 onto the scan data 10D, includes arranging multiple plates 25D so that they coincide with the normal direction of the edge line EL1. With this configuration, even the edges of teeth with complex shapes can be restored to a shape closer to the real thing.

[0204] In the fourth data 26, each of the multiple plates 25D has a disc shape. Furthermore, the centers of the multiple plates 25D may be located at the edge line EL1. This configuration can further improve the quality of the tooth scan data.

[0205] In the fourth data set 26, the multiple plates 25D are arranged at equal intervals. This configuration makes it easier to reconstruct the edges and further improves the quality of the tooth scan data.

[0206] The number of plates 25D in the fourth data set 26 is between 30 and 3500. This configuration allows for efficient improvement of the quality of the tooth scan data. For example, the more plates 25D there are, the more processing is required, which takes time to restore the edges. By setting the number of plates 25D in the fourth data set 26 to between 30 and 3500, the processing can be prevented from becoming excessive, and the tooth edges in the scan data 10D can be restored to a shape closer to the real thing.

[0207] Step ST75, which overlays the fourth data 26 onto the scan data 10D, includes obtaining the length of the edge line EL1 and the spacing between the multiple plates 25D, and determining the number of multiple plates 25D based on the length of the edge line EL1 and the spacing between the multiple plates 25D. With this configuration, the number of multiple plates 25D can be determined automatically, thus efficiently improving the quality of the tooth scan data.

[0208] Although Embodiment 4 describes an example of a method, it is not limited thereto. The method may also be implemented by a program for executing the method of Embodiment 4, or by a computer-readable recording medium on which the program for executing the method is recorded.

[0209] Furthermore, the method of Embodiment 4 may be performed by a device. For example, the device of Embodiment 4 is a device for restoring the morphology of the tooth edge portion that has been altered by scanning, and may include one or more processors, a memory storing instructions that can be executed by one or more processors, and such instructions may include the steps of the method described above.

[0210] Embodiment 4 describes an example in which the multiple plates 25D of the fourth data 26 have a disc shape, but is not limited to this. The multiple plates 25D only need to be formed in a plate shape, and may be formed in, for example, a rectangular, polygonal, or elliptical shape.

[0211] Embodiment 4 describes an example in which multiple plates 25D of the fourth data 26 are arranged at equal intervals along the edge line EL1, but is not limited to this. The multiple plates 25D do not have to be arranged at equal intervals. For example, the spacing between the multiple plates 25D may be smaller in relatively complex shaped portions of the edge line EL1 and larger in relatively simple shaped portions. For example, in portions of the edge line EL1 with a curvature greater than a predetermined value, the spacing between the multiple plates 25D may be smaller than in portions with a curvature less than or equal to the predetermined value.

[0212] In Embodiment 4, the positions of the first and last placed boards among the multiple boards 25D in the fourth data 26 may be misaligned. In this case, the method of Embodiment 4 may automatically detect the position of the last placed board and delete it if it is determined that it is at or above a predetermined distance from the first placed board.

[0213] <Examples> Examples will be described.

[0214] In Example 1, the edge portion of the tooth scan data was restored using the method of Embodiment 4, and a dental prosthesis was fabricated based on the restored tooth scan data. In Comparative Example 1, a dental prosthesis was fabricated based on untreated tooth scan data in which the edge portion was not restored. The dental prosthesis was a zirconia coping. In both Example 1 and Comparative Example 1, abutment tooth models were scanned with a scanner to obtain tooth scan data.

[0215] The dental prosthetic devices fabricated in Example 1 and Comparative Example 1 were mounted on abutment tooth models, and the lifting of the dental prosthetic devices from the abutment tooth models was evaluated.

[0216] Table 1 shows the manufacturing conditions for the dental prosthetic devices of Example 1 and Comparative Example 1.

[0217] [Table 1]

[0218] The dental prosthesis (coping) of Example 1 was fabricated using the following procedure. The dental prosthesis (coping) of Comparative Example 1 was fabricated without performing step (2) of the following procedure.

[0219] (1) Scanning of abutment tooth models A plaster abutment tooth model was used, and the abutment tooth model was 3D scanned using a dental laboratory desktop scanner (D2000, 3shape).

[0220] (2) Estimation and restoration process of the edge portion The acquired scan data was processed using general-purpose 3D CAD software (Rhinoceros 3D, Robert McNeel & Associates) to restore the margins and angles of the abutment teeth using the method of Embodiment 4.

[0221] (3) Design of coping Unprocessed scan data and data processed using the method of Embodiment 4 were imported into dental CAD software (Dental Designer 2021, 3shape Inc.) to design the coping. The design conditions were a minimum thickness of 0.5 mm, a cement gap of 0.005 mm, and an additional cement gap of 0.025 mm, with other parameters set to preset values.

[0222] (4) Creation of processing data Data from two coping conditions was imported into CAM software (GO2dental ver 6.04, GO2camInternational) to create machining data. The machining condition was set to fine mode.

[0223] (5) Processing using a dental milling machine A dental milling machine (DWX-52DCi, Roland DG) was fitted with milling burs (Matsukaze CAD / CAM milling burs BE-2.0-4DLC (2.0mm), BE-1.0-4-DLC, BE-0.6-4-DLC (0.6mm), Matsukaze Corporation) and dental cutting ceramics (Matsukaze Disc ZR Lucent Supra, Matsukaze Corporation). Machining data for each condition was entered, and zirconia copings were processed.

[0224] (6) Sintering of the semi-sintered body The obtained semi-sintered copings were sintered in a zirconia sintering furnace (Ostromat 664i, DEKEMA). The sintering schedule was set to the manufacturer's recommended preset value. After sintering, the inner surface of the zirconia copings was sandblasted using a sandblaster (Highblaster Oval Jet, Matsukaze Co., Ltd.) and high-alumina (Matsukaze High-Alumina, Matsukaze Co., Ltd.). The sandblasting pressure was 0.3 MPa.

[0225] (7) Evaluation of the fit accuracy of zirconia copings The corners of the zirconia copings were removed under two conditions. The zirconia copings were then tried on abutment tooth models, and the removed corners were photographed at 25x magnification using a digital microscope (VHX-5000, Keyence Corporation). The margin gap and the gap (lift) of the roof portion were then measured using the two-point distance measurement function.

[0226] Holes were drilled in the corners of the copings, which are dental prosthetic devices fabricated in Example 1 and Comparative Example 1. The perforated copings were then attached to abutment tooth models, and the margins and the lifting of the copings were observed.

[0227] Figure 31 is a photograph taken from the buccal side showing the coping fabricated in Comparative Example 1 attached to the abutment tooth model. Figure 32 is a photograph taken from the buccal side showing the coping fabricated in Example 1 attached to the abutment tooth model. Figure 33 is a photograph taken from the lingual side showing the coping fabricated in Comparative Example 1 attached to the abutment tooth model. Figure 34 is a photograph taken from the lingual side showing the coping fabricated in Example 1 attached to the abutment tooth model.

[0228] As shown in Figures 31 to 34, in Example 1, the lifting of the margin and coping is smaller compared to Comparative Example 1.

[0229] Table 1 shows the measurement results of the void amounts for Example 1 and Comparative Example 1.

[0230] [Table 2]

[0231] As shown in Table 2, the amount of buoyancy in Example 1 is smaller compared to Comparative Example 1.

[0232] In Comparative Example 1, the coping was fabricated using scan data in which the tooth edges were rounded compared to the edges of the actual abutment tooth model. As a result, when the coping fabricated in Comparative Example 1 was attached to the abutment tooth model, the edges did not fit properly, and lifting was likely to occur. On the other hand, in Example 1, the coping was fabricated using scan data in which the tooth edges were restored to be closer to the edges of the actual abutment tooth model. As a result, when the coping fabricated in Example 1 was attached to the abutment tooth model, the edges fit better and lifting was less pronounced compared to Comparative Example 1.

[0233] In the methods of embodiments 1 to 4 described above, the steps may be modified, added, reduced, divided, and combined depending on the applicable environment.

[0234] In the methods of Embodiments 1 to 4 described above, the order of steps may be changed.

[0235] In this specification, terms such as "first" and "second" are used only for the purpose of explanation and should not be understood as indicating relative importance or ranking of technical features. Features limited to "first" and "second" explicitly or implicitly include one or more of such features.

[0236] As described above, the above embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and is also applicable to embodiments with appropriate changes, replacements, additions, omissions, etc.

[0237] This disclosure has been fully described in relation to preferred embodiments with reference to the accompanying drawings, but various modifications and corrections will be apparent to those skilled in this technology. Such modifications and corrections should be understood to be included therein as long as they do not deviate from the scope of the present disclosure defined by the appended claims.

[0238] (Summary of Embodiment) <First Aspect> The method according to the first aspect of the present invention is a method for restoring, by a computer, the form of the edge portion of a tooth changed by scanning, the step of acquiring scan data of a tooth, the step of drawing a closed edge line indicating the edge of the tooth in the scan data, the step of deleting the scan data of the edge portion of the tooth based on the edge line in the scan data, the step of arranging data in which a plurality of plates are arranged at intervals along the edge line over the scan data. In each of the cross-sections of the scan data cut by the plurality of plates of the data, creating a first cross-section curve and a second cross-section curve showing the outer contour line of the scan data with the deleted portion sandwiched therebetween; In each of the cross-sections of the scan data cut by the plurality of plates of the data, extending the first cross-section curve and the second cross-section curve in a direction to supplement the scan data of the deleted portion; Restoring the edge portion of the tooth based on the extended first cross-section curve and the extended second cross-section curve in each of the cross-sections of the scan data cut by the plurality of plates of the data; including.

[0239] <Second Aspect> In the method according to the second aspect of the present invention, the step of restoring the edge portion of the tooth in the first aspect is In each of the cross-sections of the scan data cut by the plurality of plates of the data, calculating an intersection point where the extended first cross-section curve and the extended second cross-section curve intersect; Connecting the calculated intersection points to create an intersection line; Restoring the edge portion of the tooth based on the intersection line; may have.

[0240] <Third Aspect> The method according to the third aspect of the present invention, in the second aspect, may further include the step of extracting a boundary line surrounding the deleted portion in the scan data; Restoring the edge portion of the tooth based on the intersection line may include creating shape data from the boundary line to the intersection line.

[0241] <Fourth Aspect> In the method according to the fourth aspect of the present invention, the step of extending the first cross-section curve and the second cross-section curve in the second or third aspect is In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve is extended while maintaining the curvature or rate of change of curvature of the first cross-sectional curve at the end of the first cross-sectional curve. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the second cross-sectional curve is extended while maintaining the curvature or rate of change of curvature of the second cross-sectional curve at the end of the second cross-sectional curve. It may have.

[0242] <Fifth aspect> In the method according to the fifth aspect of the present invention, the step of superimposing the data in any of the first to fourth aspects onto the scan data may include arranging the plurality of plates so that they coincide with the normal direction of the edge.

[0243] <Sixth aspect> In the method according to the sixth aspect of the present invention, the plurality of plates in the data in any of the first to fifth aspects may each have a disc shape. The centers of the plurality of plates may be located on the edge line.

[0244] <Seventh aspect> In the method according to the seventh aspect of the present invention, the plurality of plates in the data in any of the first to sixth aspects may be arranged at equal intervals.

[0245] <Eighth aspect> In the method according to the eighth aspect of the present invention, the step of superimposing the data in the seventh aspect onto the scan data is: To obtain the length of the edge line and the distance between the multiple boards, The number of the multiple boards is determined based on the length of the edge line and the spacing between the multiple boards. It may have.

[0246] <Ninth aspect> In the method according to the ninth aspect of the present invention, the number of the plurality of plates in the data in any of the first to eighth aspects may be 30 or more and 3500 or less.

[0247] <The tenth aspect> In the method according to the tenth aspect of the present invention, the edge portion of the tooth in any of the first to ninth aspects may include at least one of abutment teeth, cavities, maintenance grooves or the edge portion of the dental arch.

[0248] <The eleventh aspect> The program according to the eleventh aspect of the present invention causes a computer to execute the method in any of the first to tenth aspects.

[0249] <The twelfth aspect> The computer-readable recording medium according to the twelfth aspect of the present invention records a program for causing a computer to execute the method in any of the first to tenth aspects.

[0250] <The thirteenth aspect> The device according to the thirteenth aspect of the present invention is a device for restoring the form of the edge portion of the tooth changed by scanning, one or more processors, a memory storing instructions executable by the one or more processors, and has the instructions are steps of acquiring tooth scan data, drawing a closed edge line indicating the edge of the tooth in the scan data, deleting the scan data of the edge portion of the tooth based on the edge line in the scan data, steps of arranging data in which a plurality of plates are arranged at intervals along the edge line and superimposing the data on the scan data, In each of the cross-sections of the scan data cut by the plurality of plates of the data, a first cross-sectional curve and a second cross-sectional curve showing the outline of the scan data are created with the deleted portion in between. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve and the second cross-sectional curve are extended in a direction that supplements the deleted portion of the scan data. A step of restoring the edge portion of the tooth based on an extended first cross-sectional curve and an extended second cross-sectional curve in each of the cross-sections of the scan data cut by the plurality of plates of the data, Includes. [Industrial applicability]

[0251] The method for restoring tooth edges altered by scanning according to the present invention can restore tooth edges damaged by scanning. Therefore, it is useful in apparatus or methods for manufacturing prosthetic devices. [Explanation of symbols]

[0252] 10, 10A, 10B, 10C, 10D scan data 11, 11A, 11B, 11C, 11D: Edge portion before restoration 12, 12A, 12D Deleted parts 13 Remaining parts 14, 14A, 14B, 14C: Edges after restoration 15 Cavity 20 Data 1 21 board 22 Second Data 23 board 24. Data 3 25,25D board 26. Data 4 30,31 Section curve data 50 Restoration device 51 processors 52 memory 53 Communications Department 100 real teeth 101 Edge section BL1 boundary line BL11 1st boundary line BL12 2nd boundary line CL1 Crossing Line CX1,CX2,CX3 Center axis DL1 1st section curve DL2 2nd section curve DL3 3rd section curve DL4 4th section curve EL1 Edge Line P1 intersection

Claims

1. A method for computer-aided restoration of the tooth edge morphology that has been altered by scanning, Steps to obtain dental scan data, The steps include drawing a closed edge line in the scan data that indicates the edge of the tooth, which serves as a criterion for deleting the scan data of the tooth edge portion and as a criterion for arranging the multiple plates after the deletion of the scan data, based on input information from the user. The steps include: deleting the scan data of the tooth edge portion based on the edge line in the scan data; The step of placing the data in which the plurality of plates are arranged at intervals along the edge line over the scan data in the portion where the scan data of the tooth edge portion has been deleted, In each of the cross-sections of the scan data cut by the plurality of plates of the data, a first cross-sectional curve and a second cross-sectional curve showing the outline of the scan data are created with the deleted portion sandwiched in between. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve and the second cross-sectional curve are extended in a direction that supplements the deleted portion of the scan data. A step of restoring the edge portion of the tooth based on a first cross-sectional curve and a second cross-sectional curve extended in each of the cross-sections of the scan data cut by the plurality of plates of the data, Methods that include...

2. The step of restoring the edge portion of the tooth is: In each of the cross-sections of the scan data cut by the plurality of plates of the aforementioned data, the intersection point where the extended first cross-sectional curve and the extended second cross-sectional curve intersect is calculated. Connecting the aforementioned calculated intersection points to create an intersection line, To restore the edge portion of the tooth based on the aforementioned crossing line, Having, The method according to claim 1.

3. Furthermore, The scan data includes the step of extracting the boundary line surrounding the deleted portion, Restoring the edge portion of the tooth based on the aforementioned intersection line involves creating shape data from the boundary line to the aforementioned intersection line. The method according to claim 2.

4. The step of extending the first cross-sectional curve and the second cross-sectional curve is: In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve is extended while maintaining the curvature or rate of change of curvature of the first cross-sectional curve at the end of the first cross-sectional curve. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the second cross-sectional curve is extended while maintaining the curvature or rate of change of curvature of the second cross-sectional curve at the end of the second cross-sectional curve. Having, The method according to claim 2.

5. The step of overlaying the aforementioned data onto the scan data includes arranging the plurality of plates so that they coincide with the normal direction of the edge. The method according to claim 1.

6. In the aforementioned data, each of the multiple plates has a disc shape, The centers of the plurality of plates are located at the edge line. The method according to claim 1.

7. The plurality of plates in the aforementioned data are arranged at equal intervals. The method according to claim 1.

8. The step of overlaying the aforementioned data onto the scan data is: To obtain the length of the edge line and the distance between the multiple boards, The number of the multiple boards is determined based on the length of the edge line and the spacing between the multiple boards. Having, The method according to claim 7.

9. The number of plates in the aforementioned data is between 30 and 3500. The method according to claim 1.

10. The edge portion of the tooth includes at least one of the abutment tooth, cavity, retention groove, or edge portion of the dentition. The method according to claim 1.

11. A program for causing a computer to perform the method described in any one of claims 1 to 10.

12. A computer-readable recording medium storing a program for causing a computer to perform the method described in any one of claims 1 to 10.

13. A device that restores the morphology of tooth edges that have been altered by scanning, One or more processors, A memory storing instructions that can be executed by the aforementioned one or more processors, It has, The aforementioned instruction is, Steps to obtain dental scan data, The steps include drawing a closed edge line in the scan data that indicates the edge of the tooth, which serves as a criterion for deleting the scan data of the tooth edge portion and as a criterion for arranging the multiple plates after the deletion of the scan data, based on input information from the user. The steps include: deleting the scan data of the tooth edge portion based on the edge line in the scan data; The step of placing the data in which the plurality of plates are arranged at intervals along the edge line over the scan data in the portion where the scan data of the tooth edge portion has been deleted, In each of the cross-sections of the scan data cut by the plurality of plates of the data, a first cross-sectional curve and a second cross-sectional curve showing the outline of the scan data are created with the deleted portion sandwiched in between. In each of the cross-sections of the scan data cut by the plurality of plates of the data, the first cross-sectional curve and the second cross-sectional curve are extended in a direction that supplements the deleted portion of the scan data. A step of restoring the edge portion of the tooth based on a first cross-sectional curve and a second cross-sectional curve extended in each of the cross-sections of the scan data cut by the plurality of plates of the data, A device including a device.

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