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EP-4530979-B1 - DATA GENERATION PROGRAM, DATA GENERATION METHOD, AND DATA GENERATION APPARATUS

EP4530979B1EP 4530979 B1EP4530979 B1EP 4530979B1EP-4530979-B1

Inventors

  • YOSHIKAWA, HIDEKI

Dates

Publication Date
20260513
Application Date
20240925

Claims (15)

  1. A data generation program (100) configured to generate image data for checking a state of a biological tissue including a tooth and a gingiva, the data generation program (100) configured to cause a computer to perform: a display step of showing on a display (20), an oral cavity image three-dimensionally showing an oral cavity including the biological tissue; a plane setting step of setting in the oral cavity image, a crown top surface as a first plane (P1), a gingival junction surface or an alveolar bone top surface as a second plane (P2), and a root apex surface as a third plane (P3) that are orthogonal to a tooth axis, a spot setting step of setting in the oral cavity image, a first spot indicating a top of a crown portion, a second spot indicating a top of an alveolar bone or a junction between the tooth and the gingiva, and a third spot indicating a root apex portion, based on a user input or machine learning; wherein the first spot is a spot on the first plane (P1) that passes through the top of the crown portion, the second spot is a spot on the second plane (P2) that passes through the top of the alveolar bone or the junction between the tooth and the gingiva, the third spot is a spot on the third plane (P3) that passes through the root apex portion, and a calculation step of calculating a ratio between a first distance between the first spot and the second spot and a second distance between the second spot and the third spot.
  2. The data generation program (100) according to claim 1, wherein the calculation step includes causing the computer to move the first spot, the second spot, and the third spot in a measurement direction based on the user input and to calculate the ratio between the first distance and the second distance that changes depending on positions of the first spot, the second spot, and the third spot.
  3. The data generation program (100) according to claim 2, wherein the measurement direction is a direction along a tooth axis.
  4. The data generation program (100) according to claim 3, being configured to further cause the computer to set the tooth axis designated by a user based on the user input, or to set the tooth axis with an estimation model for estimation of the tooth axis based on the oral cavity image.
  5. The data generation program (100) according to any one of claims 2 to 4, wherein the calculation step includes causing the computer to move the first plane (P1), the second plane (P2), and the third plane (P3) in the measurement direction based on the user input and to calculate the ratio between the first distance and the second distance that changes depending on positions of the first plane (P1), the second plane (P2), and the third plane (P3).
  6. The data generation program (100) according to any one of claims 1 to 5, being configured to further cause the computer to set the first spot, the second spot, and the third spot designated by a user based on the user input.
  7. The data generation program (100) according to any one of claims 1 to 5, being configured to further cause the computer to set the first spot, the second spot, and the third spot with an estimation model for estimation of the first spot, the second spot, and the third spot based on the oral cavity image.
  8. The data generation program (100) according to claim 7, wherein the estimation model has a measurement target tooth surrounded by a bounding box (BB), and estimates the tooth axis, the first spot, and the third spot with a shape of the bounding box (BB) being defined as a reference.
  9. The data generation program (100) according to any one of claims 1 to 8, wherein the spot setting step includes causing the computer to have the oral cavity image viewed from a plurality of points of view shown on the display (20) based on the user input, and to set the first spot, the second spot, and the third spot in the oral cavity image viewed from a specific point of view selected from among the plurality of points of view.
  10. The data generation program (100) according to any one of claims 1 to 9, being configured to further cause the computer to add a color in accordance with the ratio between the first distance and the second distance to the tooth shown in the oral cavity image.
  11. The data generation program (100) according to any one of claims 1 to 10, being configured to further cause the computer to add a numerical value in accordance with the ratio between the first distance and the second distance to the tooth shown in the oral cavity image.
  12. The data generation program (100) according to any one of claims 1 to 11, wherein the oral cavity image is generated based on optical scanner data obtained by an optical scanner, the optical scanner data including position information of each point in a point group indicating a surface of the biological tissue, and computed tomography, CT, data obtained by CT scan of the biological tissue.
  13. The data generation program (100) according to any one of claims 1 to 12, being configured to further cause the computer to perform segmentation for each anatomical element shown in the oral cavity image.
  14. A data generation method of generating image data for checking a state of a biological tissue including a tooth and a gingiva, the data generation method comprising, as processing to be performed by a computer: a display step of showing on a display (20), an oral cavity image three-dimensionally showing inside of an oral cavity including the biological tissue; a plane setting step of setting in the oral cavity image, a crown top surface as a first plane (P1), a gingival junction surface or an alveolar bone top surface as a second plane (P2), and a root apex surface as a third plane (P3) that are orthogonal to a tooth axis, a spot setting step of setting in the oral cavity image, a first spot indicating a top of a crown portion, a second spot indicating a top of an alveolar bone or a junction between the tooth and the gingiva, and a third spot indicating a root apex portion, based on a user input or machine learning; wherein the first spot is a spot on the first plane (P1) that passes through the top of the crown portion, the second spot is a spot on the second plane (P2) that passes through the top of the alveolar bone or the junction between the tooth and the gingiva, the third spot is a spot on the third plane (P3) that passes through the root apex portion, and a calculation step of calculating a ratio between a first distance between the first spot and the second spot and a second distance between the second spot and the third spot.
  15. A data generation apparatus configured to generate image data for checking a state of a biological tissue including a tooth and a gingiva, the data generation apparatus comprising: a display (20) configured to show an image; an input device (30) configured to receive a user input; and a control device (10) configured to control the display (20) based on the user input, wherein the control device (10) is configured to cause the display (20) to show an oral cavity image three-dimensionally showing inside of an oral cavity including the biological tissue, set in the oral cavity image, a crown top surface as a first plane (P1), a gingival junction surface or an alveolar bone top surface as a second plane (P2), and a root apex surface as a third plane (P3) that are orthogonal to a tooth axis, set in the oral cavity image, a first spot indicating a top of a crown portion, a second spot indicating a top of an alveolar bone or a junction between the tooth and the gingiva, and a third spot indicating a root apex portion, based on the user input or machine learning, wherein the first spot is a spot on the first plane (P1) that passes through the top of the crown portion, the second spot is a spot on the second plane (P2) that passes through the top of the alveolar bone or the junction between the tooth and the gingiva, the third spot is a spot on the third plane (P3) that passes through the root apex portion, and calculate a ratio between a first distance between the first spot and the second spot and a second distance between the second spot and the third spot.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is based on Japanese Patent Application No. 2023-167786 filed with the Japan Patent Office on September 28, 2023. BACKGROUND Field The present disclosure relates to a data generation program, a data generation method, and a data generation apparatus configured to generate image data for checking a state of a biological tissue including a tooth and a gingiva. Description of the Background Art A periodontal disease is an infectious inflammatory disease caused by periodontal pathogenic bacteria. The periodontal disease includes diseases caused in the periodontium composed of a gingiva, cementum, a periodontal membrane, and an alveolar bone, necrotizing periodontal diseases, abscesses of the periodontium, combined periodontic-endodontic lesions, gingival recession (for example, lowering of the gingiva), recession of the alveolar bone (for example, lowering of the alveolar bone), and occlusal trauma caused by strong occlusal force or abnormal force. Progress of the periodontal disease causes inflammation of the gingiva, tooth mobility, or recession of the alveolar bone. With progress of recession of the alveolar bone, standing of a tooth becomes unstable and the tooth may come off. A method of measuring a crown root ratio is used for evaluation of stability of the tooth affected by the periodontal disease. This method uses a ratio between a length of a root portion of a tooth buried in the alveolar bone and a length of a crown portion of the tooth exposed on the outside of the alveolar bone, as an index of evaluation of stability of the tooth. Such a crown root ratio has conventionally usually been measured based on combination of examination of a radiographic image and measurement of a periodontal pocket or the like. For example, Japanese Patent Laying-Open No. 10-174693 discloses examination of a state of a tooth and a gingiva by measurement by an operator such as a dentist, of a depth of a periodontal pocket by insertion of a hand-held probe into the periodontal pocket. Further periodontal disease measurement methods are known from US 2014/234796 A1. SUMMARY In a method of examination for a periodontal disease disclosed in Japanese Patent Laying-Open No. 10-174693, the probe should be inserted in the periodontal pocket, which imposes great burdens on a patient. In addition, a result of examination for the periodontal disease may vary depending on skills of an operator who measures the depth of the periodontal pocket. The probe is inserted in and taken out of the periodontal pocket where pathogenic bacteria are present. Therefore, when the pathogenic bacteria enter a tooth with minor or no symptom via the probe, the tooth may be infected by the periodontal disease. Furthermore, in measurement of the depth of the periodontal pocket, the patient may feel pain or experience bleeding. When the patient experiences bleeding, the pathogenic bacteria may also enter the blood. When the depth of the periodontal pocket is measured at a plurality of locations of each tooth, a time period for measurement may be long. In measurement of the crown root ratio in the examination of the radiographic image, only a state of the tooth viewed in a direction of incidence of X-rays has been observed and only an image superimposed in the direction of incidence of X-rays has been obtained, and hence it is difficult to accurately measure the crown root ratio. The present disclosure was made to solve such a problem, and an object thereof is to provide a technique that allows easy and accurate measurement of a crown root ratio. The above problem is solved by the claimed subject-matter which defines the present invention. Embodiments not covered by the claimed subject-matter do not form part of the invention. The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing an application of a data generation apparatus.Fig. 2 is a block diagram showing a configuration of the data generation apparatus of Fig. 1.Fig. 3 is a diagram for illustrating setting of a measurement direction and each plane for measurement of a crown root ratio.Figs. 4 to 6 are each a diagram for illustrating exemplary setting of the crown root ratio.Fig. 7 is a diagram for illustrating an exemplary reference surface set in an oral cavity image.Fig. 8 is a flowchart for illustrating exemplary data generation processing performed by the data generation apparatus of Fig. 1.Fig. 9A is a diagram showing exemplary use of a bounding box.Fig. 9B is a diagram showing exemplary use of a bounding box.Fig. 9C is a diagram showing exemplary use of a bounding box. DESCRIPTION In the below description the same or corresponding elements in the drawings have the same reference characters allotte