JP2009148337A - Optical tomographic image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clearly display sectional images of a caries region of a tooth and of a periodontal pocket. <P>SOLUTION: A scattering suppressant is previously applied to the surface of a tooth, and after that, tomographic images of the tooth and the peripheral area are displayed by an optical interference tomographic image diagnostic apparatus. As the scattering suppressant is previously applied, scattering of light on the surface of the tooth is prevented and the light penetrates into the tooth, and therefore, a clear sectional image can be displayed. Further, the contrast of the periodontal pocket and the caries region to other regions is intensified, so that the clear image can be provided. With this structure, the caries region of the tooth and the periodontal pocket can be accurately, objectively, non-invasively and non-destructively determined, and as a result, accurate treatment and preventive measures can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dental optical tomographic image display method using a chemical for diagnosis or examination of periodontal tissue, teeth, and dental caries.

  Current national health issues include overcoming lifestyle-related diseases such as metabolic syndrome. In order to overcome this, prevention by early examination and early treatment and objective diagnosis of lifestyle-related diseases are indispensable. Dental caries that causes a decline in oral function and has a prevalence of over 90% is considered a lifestyle-related disease. Many of the current caries diagnosis techniques are mainly visual inspection, palpation, and X-ray diagnosis, and the diagnosis tends to depend on the skill and experience of the dentist. In addition, although caries detection liquid and the like are used, it is difficult to accurately detect a dental caries region. In spite of the early and appropriate diagnosis of initial dental caries such as CO and C1, the objective diagnostic technique for imaging and digitizing test values for early diagnosis of dental caries is almost advanced. Not.

  OCT was developed in the early 90s, and is a technology that applies extremely safe near-infrared light and an optical interferometer as a tomographic diagnostic method. It has been clinically applied in the ophthalmic field in Western countries and is now widely used in Japan. The principle of OCT is described in Non-Patent Document 1, for example. In the near future, OCT is not only a new diagnostic device for the oral region but also a field that has the potential to be used as a general-purpose diagnostic technique for the entire clinical field such as diagnosis of digestive organ cancer and lung cancer.

On the other hand, in order to observe the periphery of the gingiva, fluorescence measurement or X-ray imaging by laser excitation may be performed. In the case of fluorescence measurement, it is difficult to accurately grasp the depth and internal state of the pocket. Since X-ray imaging is a transmission image, the tomography cannot be detected and the resolution is low, so it is inappropriate for accurate diagnosis of the alveolar bone, and there is a risk of exposure, so simultaneous diagnosis for follow-up and therapeutic treatment There is a drawback that it cannot be used frequently. Therefore, it is required to measure the depth of the periodontal pocket in an objective, non-contact and non-invasive manner. Currently, optical coherence tomography diagnostic apparatuses (OCT apparatuses) are being studied, and applications are expected in the dental field.
Handbook of Optical Coherence Tomography, p41-43, Mercel Dekker, Inc. 2002

  With a conventional OCT apparatus, it is possible to image a tooth defect site caused by tooth caries or a softened / denatured surface layer of the tooth, but it is impossible to accurately observe the state of tooth caries or the lower surface of the tooth surface. Scattering of the decalcified part due to the progress of dental caries is very strong on the surface part, so that the probe light does not reach the deep part and is poor as image information, so it is difficult to discriminate the region changed by tooth caries. In addition, the dental caries in the lower gingival margin covered with the gingival layer has a problem that light is absorbed by the gingiva and a tomographic image of the underlying tooth cannot be clearly obtained.

  The present invention has been made paying attention to such a conventional problem, and the dental optical tomographic image display method of the present invention provides light on a dental caries site on a tooth surface, dental caries or periodontal tissue. To improve the light penetration and to clarify the dental caries area by controlling the characteristics such as scattering, specular reflection, birefringence, etc., or by applying chemicals that can penetrate into the dental caries With the goal.

  In order to solve this problem, the optical tomographic image display method of the present invention applies a reflection / scattering suppression agent to the surface of a tooth, branches light from a light source by an OCT apparatus, and irradiates a part thereof around the alveolar bone. In addition, the other branched light is incident on the reference mirror, the reflected light is made to interfere, a differential signal is detected by a photodetector, and the OCT signal acquired by the OCT apparatus is irradiated with light on the measurement object. Are continuously changed, the acquired continuous two-dimensional tomographic image is extracted, and the extracted image is displayed.

  In order to solve this problem, the optical tomographic image display method of the present invention applies a chemical solution that adjusts the refractive index so as to penetrate the dental caries portion and increase the contrast with the non-tooth dental caries portion. The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone, enters the other branched light into the reference mirror, interferes with the reflected light, and detects the difference signal with the photodetector. The OCT signal acquired by the method is used to continuously change the irradiation position of light with respect to the measurement target, extract the acquired continuous two-dimensional tomographic image, and measure and display the dental caries region.

  In order to solve this problem, the optical tomographic image display method of the present invention applies a sensitizing substance for image detection by OCT to a carious part of a tooth, branches light from a light source by an OCT apparatus, and a part thereof. Is irradiated on the periphery of the alveolar bone, the other branched light is incident on the reference mirror, the reflected light is interfered, a differential signal is detected by a photodetector, and the OCT signal acquired by the OCT apparatus is measured. In contrast, the irradiation position of light is continuously changed, the acquired continuous two-dimensional tomographic image is extracted, the image is three-dimensionally processed and rendered as a three-dimensional image, and the caries affected part is clarified.

  In order to solve this problem, the optical tomographic image display method of the present invention applies a chemical solution that generates fluorescence when the tooth part is irradiated with light when acquiring a tomographic image of the tooth part with an OCT device, The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector. Measurement of the OCT signal acquired by the OCT apparatus is performed by continuously changing the light irradiation position on the measurement object, extracting the acquired continuous two-dimensional tomographic image, and superimposing the fluorescence distribution on the OCT tomographic image. , To display.

  In order to solve this problem, the optical tomographic image display method of the present invention injects a chemical solution having a refractive index close to that of a gingival part or a tooth part into a periodontal pocket, branches light from a light source by an OCT apparatus, and a part thereof. Is irradiated on the periphery of the alveolar bone, the other branched light is incident on the reference mirror, the reflected light is interfered, a differential signal is detected by a photodetector, and the OCT signal acquired by the OCT apparatus is measured. The light irradiation position is continuously changed, and the acquired continuous two-dimensional tomographic images are extracted, and regular reflection at the boundary between the gingival part and the periodontal pocket or at the boundary between the tooth and the periodontal pocket is performed. It suppresses the light to reach the deep part of the tooth part, and measures and displays the tomographic fault even in the part covered with gingiva.

According to the present invention having such characteristics, it becomes possible to make clinical application of OCT to diagnosis of dental caries by taking advantage of non-invasive characteristics, high spatial resolution, objectivity, and synchronism of OCT. It is possible to objectively, non-invasively and non-destructively determine the dental caries region and periodontal pocket, thereby enabling accurate treatment and preventive measures.
1. On the diagnostic side, caries can be imaged and digitized under non-invasive conditions, and an appropriate and objective diagnosis can be made.
2. In terms of medical care, there is no false harm effect and it can be frequently used for diagnosis at the same time during medical care, so improvement in treatment accuracy can be expected.
3. On the medical examination side, it is possible to construct an objective oral examination system by enabling image diagnosis of initial dental caries such as CO and C1, rather than a dental examination that relies on the subjectivity of the dentist performing the intraoral examination. . Image information can be accurately provided to patients and can be effectively used for informed consent. Early objective diagnosis of dental caries enables early treatment and can be expected to contribute to the optimization of medical costs.

  FIG. 1 is a block diagram showing the overall configuration of a wavelength scanning optical tomographic display system according to Embodiment 1 of the present invention. In this figure, a low-coherent laser light source 10 that oscillates an optical signal in a certain frequency range is used as the wavelength scanning light source. The output of the laser light source 10 is given to the optical fiber 11. In the middle portion of the optical fiber 11, a coupling portion 13 is provided that causes another optical fiber 12 to approach and interfere. One end of the optical fiber 12 is provided with a collimating lens 14 that converts the optical signal obtained from the laser light source 10 through the coupling unit 13 into parallel light, and a scanning mirror 15 that scans the light. The scanning mirror 15 changes the reflection angle of parallel light by rotating within a certain range about an axis perpendicular to the paper surface. The objective lens 16 is arranged at a position for receiving the reflected light, and focuses the light on the measurement site and scans (scans) it in the horizontal direction. A reference mirror 18 is provided at the other end of the optical fiber 11 through a collimating lens 17 perpendicular to the optical axis. Here, the optical distance L1 from the coupling portion 13 to the reference mirror 18 is set equal to the optical distance L2 from the coupling portion 13 to the surface of the measurement site. A photodiode 21 is connected to the other end of the optical fiber 12 through a lens 20. The photodiode 21 is a light receiving element that receives the reflected light from the reference mirror 18 and the interference light of the light reflected by the measurement site to obtain the beat signal as an electrical signal. Here, the optical fibers 11 and 12, the coupling portion 13, the collimating lens 14, the scanning mirror 15, the objective lens 16, the collimating lens 17, and the reference mirror 18 constitute an interference optical meter.

  The output of the photodiode 21 is input to the signal processing unit 23 via the amplifier 22. The signal processing unit 25 obtains a tomographic image signal by Fourier transforming a light reception signal obtained from the interferometer, as will be described later.

  The output from the signal processing unit 23 is given to the image processing unit 24. As will be described later, the image processing unit 24 detects the height level of the periodontal pocket and the alveolar bone from the two-dimensional image, and detects the display image. The display image generated in this way is displayed by the display unit 25.

  Next, the operation of the present embodiment will be described. In this embodiment, a scattering suppression chemical solution that suppresses light scattering is applied to the tooth surface in advance before measurement. As this medicine, for example, an MS coat in which an aqueous emulsion (A) solution of a 5% methyl methacrylate-p-styrenesulfonic acid copolymer and a 2.13% oxalic acid (B) solution are mixed in an equal amount at the time of use is used. . Thus, as described above, the laser light source 10 is driven, whereby the signal light is irradiated to the reference mirror 18 and the object via the optical fiber 11, and the reflected light is obtained via the coupling portion 13. The beat frequency is obtained in the photodiode 21. It is obtained in the signal processing unit 23 by amplifying this. The signal processing unit 23 obtains a tomographic image by Fourier transforming the output of the photodiode 21. Then, the incident position of the light is changed by rotating the scanning mirror 15, whereby a two-dimensional cross-sectional image can be obtained.

  By applying an appropriate medicine in this manner, scattering on the surface is reduced, light reaches the deep part, and an OCT image up to a deeper region can be clearly displayed. Further, a three-dimensional cross-sectional image can be obtained by moving the interferometer itself or the measurement object in a direction perpendicular to the light scanning direction by the scanning mirror 15.

  Moreover, you may make it apply | coat MS coat mentioned above to dental caries. This chemical solution easily penetrates into the softened dental caries portion and hardly penetrates into the healthy portion. That is, if a boundary having a large refractive index difference is intentionally created, the boundary of the dental caries region is clearly imaged by regular reflection.

  Next, FIG. 2A is a diagram showing an example of a tomographic image of a tooth in a state where there is no caries and a state where no medicine is applied, and FIG. 2B is a diagram showing a tomographic image of a tooth when the above-described MS coat is applied. As shown in these figures, when a substance is applied, reflection of the surface can be suppressed, and the internal state can be recognized more clearly.

  FIG. 3A is a diagram showing a tomographic image of a tooth in the initial caries C1 state when no substance is applied, and FIG. 3B is a diagram showing a tomographic image of the same part when an MS coat is applied. As shown in these drawings, surface reflection can be suppressed by applying a substance. Moreover, scattering of light at the caries portion can be prevented, and the internal state can be accurately grasped.

  The material to be applied is not limited to the above-described MS coating, and various materials can be used. For example, a chemical solution having a refractive index close to that of the periodontal tissue may be selected as the application substance. And by applying and injecting into the periodontal pocket, the regular reflection at the boundary between the gingival part and the periodontal pocket and the boundary between the tooth and the periodontal pocket is suppressed, the light reaches the deep part of the tooth part, and the gingiva Even in the covered part, the tooth slice can be clearly imaged.

  Furthermore, by selecting a drug solution with a low refractive index as the application substance and applying and injecting it into the periodontal pocket, the boundary between the teeth and the gingival part is clarified, and the attachment part of the entire periodontal pocket and the bottom of the pocket is more visible on the OCT image. Can be drawn clearly.

Here, if the coating material is a chemical solution that acts on light and generates fluorescence, etc., dental caries can be detected by recording the emission distribution of the fluorescence at the time of the OCT image.

It is a block diagram which shows the optical tomographic image display apparatus by embodiment of this invention. It is a figure which shows an example of the tomographic image of a tooth in the state which has not applied the chemical | medical agent in the state without a caries. The figure which shows the tomographic image of a tooth | gear at the time of apply | coating MS coat It is a figure which shows an example of the two-dimensional image by this Embodiment. It is a figure which shows the tomographic image in the case of not applying a substance of the tooth in the state of initial caries C1. It is a figure which shows the tomographic image in the state which applied the MS coat of the tooth in the state of the initial caries C1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 11,12 Optical fiber 13 Branch part 14,17 Collimating lens 15 Movable mirror 16 Objective lens 18 Reference mirror 21 Photodiode 23 Signal processing part 24 Image processing part 25 Display part

Claims (5)

Apply a reflection / scattering inhibitor to the tooth surface,
The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector.
The OCT signal acquired by the OCT apparatus is continuously changed in the irradiation position of light with respect to the measurement object, and the acquired continuous two-dimensional tomographic image is extracted.
An optical tomographic image display method for displaying the extracted image. Apply a chemical solution that adjusts the refractive index so that it penetrates the carious part of the tooth and increases the contrast with the non-dental carious part,
The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector.
The OCT signal acquired by the OCT apparatus is continuously changed in the irradiation position of light with respect to the measurement object, and the acquired continuous two-dimensional tomographic image is extracted.
An optical tomographic image display method for measuring and displaying a dental caries region. Apply a sensitizer to the carious part of the tooth for image detection with OCT,
The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector.
The OCT signal acquired by the OCT apparatus is continuously changed in the irradiation position of light with respect to the measurement object, and the acquired continuous two-dimensional tomographic image is extracted.
An optical tomographic image display method for performing three-dimensional processing of an image and rendering it as a three-dimensional image to clarify a caries affected part. When acquiring a tomographic image of a tooth with an OCT apparatus, when a tooth is irradiated with light, a chemical solution that generates fluorescence is applied,
The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector.
The OCT signal acquired by the OCT apparatus is continuously changed in the irradiation position of light with respect to the measurement object, and the acquired continuous two-dimensional tomographic image is extracted.
An optical tomographic image display method for measuring and displaying the fluorescence distribution superimposed on an OCT tomographic image. Inject a drug solution with a refractive index close to that of the gingiva or teeth in the periodontal pocket,
The OCT device divides the light from the light source and irradiates a part of the light to the periphery of the alveolar bone. The other branched light is incident on the reference mirror, the reflected light is interfered, and the differential signal is detected by the photodetector.
The OCT signal acquired by the OCT apparatus is continuously changed in the irradiation position of light with respect to the measurement object, and the acquired continuous two-dimensional tomographic image is extracted.
Suppresses regular reflection at the boundary between the gingiva and the periodontal pocket, or at the boundary between the tooth and the periodontal pocket. Optical tomographic image display method for measurement and display.

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