WO2014013950A1 - 歯垢、歯肉及び歯槽骨の計測表示方法及び計測表示装置 - Google Patents
歯垢、歯肉及び歯槽骨の計測表示方法及び計測表示装置 Download PDFInfo
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Definitions
- the present invention relates to a measurement display device and a measurement display method for plaque, gingiva and / or alveolar bone.
- the present invention displays dental plaque existing in a tooth surface and interdental portion, a gingival crevice portion, and a periodontal pocket including a tooth adjacent surface and a tooth occlusal surface as a two-dimensional and three-dimensional images, and a plaque.
- the present invention relates to a gingival and / or alveolar bone measurement and display method and a measurement display device capable of quantifying bone and obtaining gingival swelling and / or change in alveolar bone.
- the plaque staining method is a method using a plaque stain solution.
- O'leary's Plaque is used in Japan's dental insurance medicine.
- Control Record PCR method
- the PCR method is a method of dividing the tooth surface into four surfaces, obtaining the ratio of the number of attached surfaces to the total number of tooth surfaces, and evaluating the oral cleaning state.
- this method is a two-step evaluation method with and without, and lacks detail in grasping the state of plaque adhesion.
- plaque staining operation itself gives the patient strong discomfort, and the removal of the staining solution after staining is complicated. Furthermore, since parts other than plaque are also stained, there are many inconveniences such as low specificity of the inspection method. Therefore, it cannot be said to be a sufficient method for spreading the recognition of the importance of oral cleaning.
- the Loe-Silness plaque index is known as a method for evaluating the plaque removal effect of various brushing methods and electric toothbrushes. Since this method does not perform staining, the boundary between dental plaque and the tooth and periodontal tissue becomes unclear.
- the evaluation criteria are set to 4 levels with no adhesion, tactile, visible and a large amount. However, it is not a quantitative evaluation method because of the large difference in stage.
- the dental plaque evaluation method in the Oral Hygiene Evaluation Method is converted into a score, which makes it seemingly numerical and has objectivity.
- it is a problem that it is inferior in reproducibility and lacks objectivity, and the numerical value is not consistent among examiners, and it cannot be said that it is sufficiently spread in dental clinics.
- Patent Document 1 As an evaluation method premised on plaque staining, the method described in Patent Document 1 is known. This method uses a dentifrice to which 0.01 to 2.0% by weight of a fluorescent dye is added, attaches the fluorescent dye to the plaque during brushing, and irradiates incandescent light or fluorescent light through an appropriate filter. By doing so, light is emitted, and the degree of plaque is detected from the state of light emission.
- Patent Document 2 also discloses a plaque staining method.
- Patent Document 3 discloses a method in which a pigment and light are used in combination. Although the principle is that the dye is excited by light and emits fluorescence, the dye itself needs to adhere strongly to the plaque. In addition, fluorescent pigment groups such as chlorophyll and fluorescein are not sufficiently stained for plaque.
- patent document 4 is disclosing the method of detecting dental plaque only with specific light. However, this method has a problem that it is impossible to detect plaque in the initial stage of formation.
- Non-Patent Document 1 discloses a method of taking an intraoral photograph as a digital image after plaque staining and calculating the dental plaque area relative to the tooth surface electronically.
- this method is difficult to distinguish between plaque and gingiva. Since the optical photograph only captures the object in a plane, there is a high possibility that the evaluation is different between the front part and the rear part.
- QLF method Quantitative light-fluorescence method
- plaque is visually distinguished from the surrounding tissue.
- Non-Patent Document 2 discloses a method of collecting impressions before and after removing plaque, performing a digital three-dimensional scan on the front and rear plaster models, and three-dimensionally evaluating plaque adhesion.
- the impression twice before and after is complicated and its practicality in the clinical field is extremely low.
- plaque measurement and evaluation from a plaster model is not realistic.
- Patent Document 5 a dental OCT device has been developed and used for caries diagnosis. However, it only mentions how to measure caries.
- the present invention has been made in view of the above problems. In other words, it overcomes the drawbacks of conventional methods, performs non-contact and non-invasive quantitative measurement of plaque, displays it as 2D and 3D images, plaque thickness, length, plaque cross-sectional area and surface area It is an object of the present invention to provide a plaque measurement and display method and apparatus capable of calculating plaque volume and performing an objective evaluation method of plaque adhesion with high reproducibility without difference between examiners.
- dental plaque gingiva and alveolar bone, which are periodontal tissues, are measured non-contactly and non-invasively and displayed as two-dimensional and three-dimensional images to show the amount of change in gingiva and alveolar bone.
- An object of the present invention is to provide a measurement and display method and apparatus for gingiva and / or alveolar bone that can be obtained.
- a method for measuring and displaying dental plaque the step of dividing near-infrared light output from a light source into measurement light and reference light, and the measurement light on teeth in the oral cavity.
- An optical coherence tomographic image based on a step of sweeping while irradiating toward, a step of obtaining interference light from the reflected light and backscattered light obtained from the tooth and the reference light, and a scattering intensity value of the interference light
- plaque refers to a biofilm made up of oral bacteria, mutan, insoluble glucan, saccharides, and the like, which are actually attached to the tooth surface to be measured.
- plaque area refers to an area that is extracted as a portion indicating plaque and displayed as plaque on the displayed optical coherence tomographic image in the plaque measurement and display method according to the present invention. Shall. From the same viewpoint, the following “gingiva” and “gingival region”, “alveolar bone” and “alveolar bone region”, and “enamel” and “enamel region” are also distinguished.
- the optical coherence tomographic image is a two-dimensional optical coherence tomographic image that is two-dimensionally displayed by distinguishing the plaque region, the enamel region where the plaque is deposited, and the gingival region.
- the optical coherence tomographic image is a three-dimensional optical coherence tomographic image displayed by distinguishing a plaque part region, an enamel part region in which plaque is deposited, and a gingival part region into a three-dimensional image. It is preferable that
- the optical coherence tomographic image includes a two-dimensional optical coherence tomographic image that is displayed two-dimensionally while distinguishing between a plaque part region, an enamel part region in which plaque is deposited, and a gingival region. It is preferable that both the plaque part region, the enamel part region where the plaque is deposited, and the gingival part region are distinguished from each other, and the three-dimensional optical coherence tomographic image is displayed as a three-dimensional stereoscopic image.
- the step of quantifying the plaque includes a step of quantifying the thickness and / or length of the plaque from the plaque region extracted from the two-dimensional optical coherence tomographic image.
- the step of quantifying the plaque includes a step of quantifying the volume of the plaque from the plaque region extracted from the three-dimensional optical coherence tomographic image.
- the step of quantifying the plaque may be a method including a step of quantifying a cross-sectional area of plaque from a plaque region extracted from the two-dimensional optical coherence tomographic image or the three-dimensional optical coherence tomographic image. preferable.
- the step of quantifying the plaque includes a step of quantifying the surface area of the plaque from the plaque region extracted from the three-dimensional optical coherence tomographic image.
- the method further includes a step of creating a database of the determined values and a step of displaying the determined values as one or more selected from an image, a table, and a graph over time.
- a measurement display device for plaque a light source that outputs near-infrared light, a branching unit that divides the near-infrared light into measurement light and reference light, and the measurement
- a plaque measuring probe that sweeps while irradiating light toward a tooth in the oral cavity, a light receiving element that receives interference light obtained from reflected light and backscattered light obtained from the tooth, and the reference light, and A computer that converts the scattering intensity value of the interference light into a gradation value and gives an optical coherence tomographic image; an extraction and measurement unit that extracts a plaque region and quantifies plaque; and an optical coherence tomographic image And a display unit for displaying the quantitative result.
- software for causing a computer to execute a method for measuring and displaying plaque, wherein an optical coherence tomographic image is based on the scattered light intensity value obtained by the above-described method.
- a step of extracting a plaque region based on the scattered light intensity value of the interference light a step of imaging the plaque region, and a plaque based on the extracted plaque region.
- Software for causing a computer to execute a method for measuring and displaying plaque, wherein an optical coherence tomographic image is based on the scattered light intensity value obtained by the above-described method.
- the step of morphologically identifying plaque, gingiva, and enamel on the optical coherence tomographic image based on anatomical facts it is preferable to cause a computer to execute the method further including the method.
- the method further includes a step of creating a database of the values obtained in the step of obtaining the quantified value, and a step of displaying the quantified value over time as one or more selected from an image, a table, and a graph.
- the method is executed by a computer.
- a measurement and display method for gingiva and / or alveolar bone the step of dividing near-infrared light output from a light source into measurement light and reference light, and the measurement A step of sweeping light while irradiating the teeth and periodontal tissue in the oral cavity, a step of obtaining interference light from the reflected light and backscattered light obtained from the teeth and periodontal tissue, and the reference light; , Based on the scattered light intensity value of the interference light, obtaining an optical coherence tomographic image, extracting a gingival and / or alveolar bone region having a specific scattered intensity value, and quantifying the gingiva and / or alveolar bone And a step of imaging the gingiva and / or alveolar bone, and performing the step of quantifying the gingiva and / or alveolar bone over time, thereby increasing the amount of gingival swelling and / or alveolar bone change The step of obtaining is further included.
- a gingival and / or alveolar bone measurement display device a light source that outputs near-infrared light, and a branching unit that divides the near-infrared light into measurement light and reference light, A measurement probe that sweeps while irradiating the measurement light toward the teeth and periodontal tissues in the oral cavity, the reflected light and backscattered light obtained from the teeth and periodontal tissue, and the reference light.
- a light receiving element that receives the interference light, a calculation unit that converts the scattering intensity value of the interference light into a gradation value, and provides an optical coherence tomographic image, and extracts a gingival and / or alveolar bone region, and gingiva and / or
- An extraction and measurement unit that quantifies alveolar bone and a display unit that displays an optical coherence tomographic image and a quantification result are provided.
- a gingival and / or alveolar bone measurement and display method based on the scattered light intensity value of interference light obtained by the above-described method.
- a step of obtaining an optical coherence tomographic image a step of extracting a gingiva and / or alveolar bone region based on the scattering intensity value of the interference light, and imaging the gingival region and / or alveolar bone region
- a step of quantifying the gingiva and / or alveolar bone based on the extracted gingival region and / or alveolar bone region a step of quantifying the gum and / or alveolar bone over time
- the computer a gingival swelling and / or alveolar bone change by the computer.
- the method and apparatus according to the present invention have the following features and are effective in towing more reliable dental care.
- objectivity / University Conventionally, in clinical dentistry and dental examinations, subjective examination methods such as visual inspection and palpation have mainly been used, and the values have varied.
- the present invention can provide an evaluation method for objectively quantifying plaque, gingiva and alveolar bone.
- the extraction of the plaque region on the image is automatically performed using a computer without human intervention, so any inspector in any country can perform the extraction.
- similar data can be acquired, reproducibility is good, and it can be used universally.
- the method and apparatus according to the present invention can perform quantitative measurement, the reproducibility and reliability are high. Moreover, measurement and evaluation over time are possible. It can be applied to dental examinations for imaging and digitization, and can be provided as a numerical database.
- safety Since the method and apparatus according to the present invention uses near-infrared light as observation light, it can be inspected without medical exposure, which is inevitable with the conventional dental X-ray method. Furthermore, since this is a non-contact and non-invasive test method, the test can be performed without destroying the adhesion structure of periodontal tissue and without seeding bacteria in the surrounding periodontal pocket.
- FIG. 3A is a schematic view of a dental plaque measuring probe tip and a tooth as viewed from above
- FIG. 3B is a dental plaque measuring probe tip and a dental plaque measuring probe tip. It is the schematic when seeing from the front of, and has shown X, Y, and Z-axis direction in this specification.
- FIG. 4A is a schematic view of a dental plaque measuring probe viewed from the side when the tooth axis of the subject tooth and the incident angle of the observation light are inappropriate
- FIG. 3A is a schematic view of a dental plaque measuring probe viewed from the side when the tooth axis of the subject tooth and the incident angle of the observation light are inappropriate
- FIG. It is the schematic when a tooth axis of this and the incident angle of observation light are appropriate.
- FIG. 5A is a schematic diagram when the dental measurement probe is viewed from the top, and the imaging tooth surface of the tooth as the subject and the incident angle of the observation light are inappropriate and the distance between the subjects is inappropriate.
- (B) is a schematic diagram when the photographing tooth surface of the tooth and the incident angle of the observation light are appropriate and the distance between the subjects is appropriate. It is a graph which shows the relationship between the time and frequency axis which were converted into the electrical signal with the light receiving element. It is a graph which shows the relationship between the depth distance after a fast Fourier transform, and scattering intensity.
- FIG. 8A is a graph showing the relationship between the depth distance and the scattering intensity after the fast Fourier transform, and FIG.
- FIG. 8B is a matrix matrix in which the numerical values of the depth distance and the scattering intensity are arranged in one column.
- (C) is a matrix matrix obtained by profiling the matrix matrix of (B).
- FIG. 9A is a matrix matrix in which scattering intensity is profiled
- FIG. 9B is a two-dimensional optical coherence tomographic image in which a difference in contrast is imaged according to a scale for visualization. It is a two-dimensional optical coherence tomographic image in which a plaque area, an enamel area, and a gingival area are recognized in an imaging area.
- FIG. 13A is a two-dimensional optical coherence tomographic image of the gingiva of a patient suffering from gingivitis
- FIG. 13B is a two-dimensional optical coherence tomographic image of a normal patient's gingiva, measuring the cross-sectional area
- FIG. 14 is a two-dimensional optical coherence tomographic image of the alveolar bone, schematically showing the measurement of the cross-sectional area.
- FIG. 15 (A) is an intraoral photograph of plaque deposited by a conventional staining method
- FIG. 15 (B) is an image of the plaque region obtained quantitatively measured and displayed in this embodiment. It is an image.
- FIG. 16A is an optical coherence tomographic image capturing the deposition of subgingival plaque
- FIG. 16B is a schematic diagram of plaque deposition.
- FIG. 17 is an explanatory diagram for explaining a fiber probe that is preferably used for measuring plaque on the tooth adjacent surface and the tooth occlusal surface.
- FIG. 18 is a schematic diagram showing rotation of a fiber probe for dental plaque measurement and an irradiation range of laser light.
- FIG. 19 is an explanatory diagram for explaining a method for photographing a tooth adjacent surface from the cheek side surface.
- FIG. 20 is an explanatory diagram for explaining a method for photographing a tooth adjacent surface, which is the aa cross section of FIG.
- FIG. 21 is an explanatory diagram illustrating a method for photographing a tooth adjacent surface from the occlusal surface.
- FIG. 22 is a method for photographing dental plaque on the tooth occlusal surface.
- FIG. 22A is a diagram for explaining the horizontal movement of the probe
- FIG. 22B is a diagram for explaining the vertical movement of the probe. .
- the present invention is a plaque measurement display device.
- the plaque measurement display device is a device that selectively measures plaque, in particular, using an OCT (Optical Coherent Tomography: OCT) device.
- OCT Optical Coherent Tomography
- the OCT apparatus is an apparatus capable of measuring a living tissue in a micro order with extremely high resolution. Further, in the OCT apparatus, by using a near-infrared light source that can reach the body surface, it is possible to measure not only the surface portion of the subject but also the deep portion.
- the OCT apparatus is particularly preferably a wavelength scanning OCT (Swept source-OCT) which is a Fourier domain OCT.
- FIG. 1 is a block diagram showing an outline of a plaque measurement display device according to this embodiment.
- 1 mainly includes a near-infrared light source 1, a branching unit 3, a collimating lens L1, a reference mirror 9, a plurality of optical fibers F 1 , F 2 , F 3 , F 4 and a rectifier 4.
- the optical interferometer unit, the plaque measuring probe 8, the light receiving element 10, the preamplifier (amplifying device) 11, the computer unit 12, the measuring unit 13, and the display unit 14 are substantially configured. Is done.
- a light source 1 is a wavelength scanning light source that oscillates an optical signal in a certain range, for example, 1310 to 1360 nm.
- Light source 1 is connected to the optical fiber F 1
- the optical fiber F 1 is connected to the branch unit 3.
- An optical rectifier 4, a light modifier 5, a polarizing plate, and an attenuation plate 6 are sequentially provided in the subsequent stage of one optical fiber F 2 a branched at the branching section 3.
- a plaque measuring probe 8 is connected to the rear stage of the attenuation plate 6 via a light transmission / reception bundled optical fiber F 2b .
- the collimating lens L1 and the reference mirror 9 is provided downstream of the another optical fiber F 3 which is branched at the branch portion 3.
- an optical path length adjustment unit may be installed in the configuration of the apparatus 100 after the optical fiber F 2a and before the optical fiber F 3 .
- the preamplifier 11 After signal amplification by the preamplifier 11, the preamplifier 11 is connected to the computer unit 12 via an electric signal conductor.
- the computer unit 12 is further connected to a measuring unit 13 and a display unit 14.
- the computer 12 is further connected to a laser position sensor (not shown) of the probe 8.
- the near-infrared light source 1 is a light source that generates near-infrared light in a wavelength band that is non-invasive to a living body.
- a laser light source that oscillates an optical signal having a single spectrum for example, a wavelength scanning fiber light source disclosed in Japanese Patent Application Laid-Open No. 2006-80384 can be used.
- the oscillation wavelength for example, it is preferable to use a 1.3 ⁇ m band that absorbs less water and causes less scattering.
- the wavelength scanning range may be, for example, a range of 100 nm to 200 nm, and the sweep speed may be, for example, 20 kHz, but is not limited to such a value.
- the branching section 3 can be connected to an optical fiber and can split light at a desired ratio or can be synthesized.
- the light receiving element 10 is a device for converting the interference light coming from the optical fiber F 4 into an electrical signal, in addition to photodiodes, or the like can also be used balanced photo detector.
- the preamplifier 11 further amplifies the electric signal obtained from the photodiode.
- the computer unit 12 and the measurement unit 13 may be software loaded on a computer, and may be configured as an integral unit without being distinguished from each other.
- the computer unit 12 performs fast Fourier transform on the electrical signal from the preamplifier 11 to calculate scattering intensity value data, and stores the data.
- the computer 12 also stores data for generating a three-dimensional image based on the position signal from the position sensor of the probe 8. Also, the scattering intensity value data is converted and stored as gradation value data.
- the measurement unit 13 extracts the plaque region from the scattered intensity value and gradation value data. Alternatively, an operation of measuring a specific length or distance on the image-displayed data or extracting the number of pixels or the number of voxels is performed.
- the display unit 14 may be a computer display device.
- the display unit 14 displays various images obtained by the measurement unit 13 and calculated numerical values.
- the dental plaque measurement probe 8 is a portion that directly irradiates the subject with observation light and receives reflected light and backscattered light.
- FIG. 2 is a schematic diagram showing the configuration of the dental plaque measurement probe 8.
- the plaque measurement probe 8 mainly includes a non-operation type optical path control mirror 81, two operation type optical path control mirrors 82, an objective lens 83, a plaque measurement probe tip 84, and an imaging position adjustment stage 86. It consists of.
- the imaging position adjustment stage 86 is provided with an imaging position adjustment X-axis control unit 87a, an imaging position adjustment Y-axis control unit 87b, and an imaging position adjustment Z-axis control unit 87c, and measures plaque on the teeth that are subjects.
- an imaging position adjustment ⁇ -axis control unit is provided to control the position of the plaque measurement probe with respect to the tooth that is the subject. Configured to be able to. These control units can be electrically controlled by a driving unit (not shown). A control device (not shown) that is electrically connected to the drive unit can be configured to be operated by the operator.
- the probe 8 is also provided with a laser position sensor (not shown). The laser position sensor is a position sensor that outputs a relative position signal of the probe 8, and its output is given to the computer 12.
- the illustrated plaque measurement probe 8 is an example of an anterior tooth measurement probe.
- a molar measurement probe, a caries measurement probe, or the like can be detachably provided, and these can be changed according to the purpose. be able to.
- a reflection mirror capable of refracting the observation light at 90 degrees is installed at the probe tip.
- the molar measurement probe may be configured to include a mechanism in which the tip of the probe expands and contracts so that a tooth deviating from the dentition can be photographed.
- the expansion / contraction range of the probe tip is preferably in the range of 10 ⁇ 10 mm.
- the probe tip itself preferably has a major axis of about 90 ⁇ 10 mm and a minor axis of about 10 ⁇ 2 mm. This is because it is anatomically effective.
- Such a plurality of detachable probes are described in detail in Japanese Patent Application Laid-Open No. 2011-189077.
- FIG. 17 is an explanatory diagram for explaining a fiber probe 800 that is preferably used for measuring plaque on the tooth adjacent surface and / or the tooth occlusal surface.
- the fiber probe 800 for measuring plaque includes a sheath 806 and a probe main body 801 disposed in the sheath 806.
- the probe main body 801 is connected to the end face of the optical fiber F in an axially aligned state.
- the probe main body 801 includes a prism 804, a GRIN lens (refractive index tilt lens) 803, and a connection light guide unit 802 that connects the GRIN lens 803 and the optical fiber F in order from the distal end side.
- the optical fiber F corresponds to the optical fiber F 2b in FIG.
- the prism 804 may be a right angle prism, for example, and is arranged so that the emission angle of the light guided by the optical fiber F is a right angle.
- the prism 804 may be configured so that the emission angle of the light guided by the optical fiber F is irradiated at an acute angle, for example, 60 degrees.
- the prism 804 may be configured so that the light emitted by the optical fiber F is emitted at an obtuse angle, for example, 130 degrees.
- These prisms 804 may be configured to be detachable. The light deflected by the prism 804 passes through the sheath 806 and is irradiated to the measuring object 200 existing outside.
- the sheath 806 may have a matching oil for refractive index adjustment that fills the space between the sheath 806 and the probe body 801.
- the refractive index of the matching oil may be the same or close to the refractive index of the prism 804, or the same or close to the refractive index of the sheath 806.
- the matching oil filled in the sheath 806 has a viscosity enough to ensure the rotation and back-and-forth movement of the probe 800 smoothly.
- the dental fiber measuring fiber probe 800 is provided with a rotating means 805 at the proximal end of the probe main body 801.
- the rotating means 805 preferably has an actuator provided with a motor, and the probe main body 801 is connected to the rotating shaft of the motor.
- the rotation of the probe main body 801 can be performed by the operation of a human hand.
- the rotating means 805 is not limited to the configuration provided at the proximal end of the probe main body 801, and various changes can be made. In the drawing, the direction of rotation is schematically indicated by an arrow, but the direction of rotation is not limited to the illustrated direction.
- the fiber probe 800 for measuring plaque may be provided with a moving means (not shown) provided in the sheath 806 along its longitudinal direction, and the probe main body 801 is moved inside the sheath 806 by this moving means. It can also be moved back and forth. Such back-and-forth movement can further expand the photographing range of dental plaque.
- FIG. 18 is a schematic diagram showing the rotation of the fiber type probe 800 for measuring plaque and the light emission range.
- FIG. 18A is a schematic diagram showing the direction of light emission at a rotational position of the fiber probe for measuring plaque. For the sake of explanation, description of the sheath is omitted, and only the probe main body 801 is shown.
- FIG. 18B is a schematic diagram showing the direction of light emission when the dental fiber measuring probe 800 is rotated 360 degrees. By using the fiber probe 800 rotated 360 degrees, the direction of light emission from the probe main body 801 can be set to an arbitrary direction of 360 degrees around the probe main body 801. With the configuration of the dental fiber measuring fiber probe 800, any living tissue including dental plaque can be tomographically imaged 360 degrees in real time.
- the tooth adjacent surface which is the surface where the teeth are in contact with each other, is very narrow, it is less cleanable and self-cleaning than other tooth surfaces. Therefore, it is easy to deposit plaque, and it is easy to become an unclean area, and it is considered as one of the three most common sites of caries.
- the plaque dyeing method which is the gold standard for evaluation of plaque deposition, is not applicable because the adjacent tooth surface cannot be confirmed by visual inspection.
- As a classic method of evaluating dental caries on the adjacent tooth surface there is a method of inserting an instrument between teeth and separating the teeth in order to look directly at the adjacent surface. Are listed. However, it has not been widely used because of the time required for the separation between teeth and pain and discomfort.
- the fiber type probe used for the caries measurement of the adjacent surface by the present inventors is disclosed in JP 2011-189078 A
- the fiber type probe used for the caries measurement of the occlusal surface is JP 2011-217973 A. It is disclosed in the gazette.
- the OCT probe for caries measurement can be applied to plaque measurement on the adjacent surface and plaque measurement on the occlusal surface, respectively.
- a light source 1 generates near-infrared light in a wavelength band that is non-invasive to a living body, for example, around 1300 nanometers.
- the light transmitted by the optical fiber F 1 is split into reference light and observation light at the branching section 3.
- the divided observation light passes through the optical rectifier 4 and is transmitted by the optical fiber F 2a, and is polarized and attenuated by the light modifier 5 by the polarizing plate, the attenuation plate 6 and the like.
- the light whose wave axis is arranged is transmitted to the dental plaque measurement probe 8 through the optical fiber F 2b bundled with light transmission and reception.
- the light transmitted to the plaque measuring probe 8 is subjected to optical path control by the non-operating optical path control mirror 81 and the active optical path control mirror 822 such as a galvano mirror or MEMS mirror shown in FIG.
- a raster orbit is formed.
- the light accompanied by the raster-like trajectory is focused by the objective lens 83, passes through the tip 84 of the dental plaque measurement probe, and is used as observation light for dental plaque, enamel, and ivory as the subject 200. Depending on the quality and imaging range, it reaches the gingiva and alveolar bone of the periodontal tissue.
- FIG. 3A is a conceptual diagram of the plaque measurement probe 8 and the subject 200 as viewed from above the probe in FIG.
- the direction of the observation light 302 inward from the tooth surface of the subject 200 is set as the Z axis in the depth direction.
- FIG. 3B is a conceptual diagram of the probe viewed from the front of the probe. Photographing is performed so that the tooth of the subject 200 enters the field of view 301 indicated by the virtual line.
- an X axis and a Y axis perpendicular to the direction of the observation light 302 from the back side to the front side of the paper are set.
- FIG. 4A is a diagram showing a case where the angle between the tooth axis 303 of the subject 200 and the observation light 302 is inappropriate in measurement
- FIG. 4B is a diagram showing a proper case.
- the angle ⁇ between the axis 304 parallel to the observation light 302 and the tooth axis 303 is close to R (90 degrees)
- the angle between the subject 200 and the observation light 302 is appropriate.
- the angle ⁇ is preferably in the range of 85 to 95 degrees.
- FIG. 5A is a diagram illustrating a case where the angle between the axis 305 parallel to the tooth surface of the subject 200 and the observation light 302 and the distance between the subject 200 and the probe 8 are inappropriate in the measurement.
- FIG. 5A is a diagram illustrating a case where the angle between the axis 305 parallel to the tooth surface of the subject 200 and the observation light 302 and the distance between the subject 200 and the probe 8 are inappropriate in the measurement.
- 5B is a diagram illustrating a case where the angle between the axis 305 parallel to the tooth surface of the subject 200 and the axis 306 parallel to the observation light 302 and the distance 307 between the subject 200 and the probe 8 are appropriate.
- the angle ⁇ between the axis 304 parallel to the observation light 302 and the axis 305 parallel to the tooth surface is close to R (90 degrees)
- the angle between the subject 200 and the axis 306 parallel to the observation light 302 is appropriate.
- the angle ⁇ is also preferably in the range of 85 to 95 degrees.
- the distance 307 between the subject 200 and the probe 8 is preferably 1 to 5 mm.
- the fiber-type probe 800 for measuring plaque can be advantageously used particularly for measuring plaque on the tooth adjacent surface and the tooth occlusion surface.
- FIG. 19 is an explanatory view for explaining a photographing method from the buccal side of the tooth adjacent surface according to the present embodiment
- FIG. 20 is a cross-sectional view along aa in FIG.
- a fiber probe 800 for measuring plaque is inserted into the upper part or the lower part of the interdental hour space, and the sheath 806 is fixed in the interdental hour space where the probe 800 is inserted.
- the fiber measuring probe 800 for measuring plaque is between the tooth 200a and another tooth 200b, and can directly photograph the adjacent tooth surface.
- the sheath 806 Since the sheath 806 has flexibility, it is easy to insert the fiber probe 800 for measuring plaque into the interdental space and it is difficult to damage periodontal tissue in the vicinity of the interdental space. Then, while rotating the probe main body 131 by the rotating means 805, an image of the tooth adjacent surface is taken with the fiber probe 800 for measuring plaque. Alternatively, the probe main body 801 can be moved forward or backward by moving means (not shown) in the fixed sheath 806, and an image of the tooth adjacent surface can be taken with the fiber probe 800 for measuring plaque.
- the probe main body 801 is moved forward or backward by a moving means (not shown) in the fixed sheath 806, and an image of the tooth adjacent surface is displayed as a fiber type for plaque measurement. Images can be taken with the probe 800.
- the probe body 801 rotates 360 degrees, but is not limited to this.
- the fiber probe 800 for measuring plaque when inserted in the upper part of the interdental space, it can be rotated 180 degrees downward.
- plaque measurement is performed in the lower part of the interdental space.
- the probe main body 801 may be moved forward or backward together with the sheath 806 and an image of the adjacent tooth surface may be taken with the fiber probe 800 for measuring plaque. Is possible.
- a sheath moving means for moving the sheath 806 can be provided without providing a moving means for moving the probe main body 801 back and forth within the sheath 806.
- the sheath 806 is formed in a double configuration formed by an outer sheath and an inner sheath, the outer sheath is fixed in the interdental space, and the probe body 801 is moved forward or backward together with the inner sheath. It is also possible to take an image of the tooth adjacent surface.
- FIG. 21 is a diagram for explaining a further usage mode of the fiber type probe 800 for measuring plaque.
- FIG. 21A shows a usage mode of a fiber probe 800 for measuring plaque having a first probe body 801a having a prism configured so that the light emission angle is a right angle.
- FIG. 21C shows a usage mode of a fiber probe 800 for measuring plaque having a second probe body 801b having a prism configured so that the light emission angle is an acute angle.
- FIG. 21C shows the light emission angle.
- It is a usage mode of the fiber probe 800 for plaque measurement which has the 3rd probe main body 801c provided with the prism comprised so that it may become an obtuse angle.
- different probe bodies with prisms that achieve different exit angles may be composed of the three types described above, and these probe bodies can be used interchangeably. That is, in the normal usage mode, as shown in FIG. 21A, the first probe body 801a is used. Then, when the dental fiber measuring fiber type probe 800 is inserted into the back side of the interdental space, and the tooth adjacent surface is photographed from the back side, as shown in FIG. 21B, the second probe is used. The main body 801b is used. In addition, since the lower part of the interdental space is narrow, when it is difficult to insert the fiber probe 800 for measuring plaque, the third probe body 801c is used as shown in FIG. Thus, even when the lower part of the interdental space is narrow and it is difficult to insert the fiber probe 800 for measuring plaque, it is possible to accurately photograph the adjacent tooth surface by properly using a plurality of probe bodies according to the purpose. It becomes possible.
- FIG. 22 is an explanatory diagram for explaining a method for photographing a tooth occlusal surface using a fiber type probe 800 for measuring plaque.
- 22A is a diagram for explaining movement of the fiber probe 800 for measuring plaque in a direction horizontal to the occlusal surface
- FIG. 22B is a diagram perpendicular to the occlusal surface of the fiber probe 800 for measuring plaque. It is a figure explaining the movement to a simple direction.
- the description of the sheath 806 and the rotating means 805 is omitted in FIG.
- Plaque measurement fiber probe 800 is arranged in the vicinity of the tooth occlusion surface. Since the sheath 806 is flexible, it does not easily damage periodontal tissue.
- the rotation range angle of the probe main body 801 needs to be a rotation range angle that can cover the form of the tooth occlusal surface by the rotation of the probe main body 801, and is not particularly limited. is there. Note that the probe body 801 is rotated without moving back and forth to photograph plaque with the fiber probe 800 for measuring plaque, or the probe body 801 is moved back and forth without rotating and used for measuring plaque. It is also possible to photograph dental plaque with the fiber type probe 800. Then, as shown in FIG.
- the dental fiber measuring probe 800 is moved horizontally (front / rear / left / right) by a horizontal moving means (not shown), and the tooth occlusal surface with respect to the horizontal position is obtained. OCT imaging according to the form can be performed. Further, as shown in FIG. 22B, in some cases, the dental fiber measuring fiber probe 800 is moved vertically (up and down) by a vertical movement means (not shown) to keep the distance from the observation target 200 constant. Thus, OCT imaging according to the shape of the tooth occlusal surface can be performed with good sensitivity and resolution.
- the observation light emitted from the plaque measurement probe 8 or the plaque measurement fiber probe 800 according to a specific embodiment and reaching the subject is optically reflected, scattered, or absorbed. causes a physical phenomenon.
- the reflected light and the backscattered light returning to the same axis are transmitted to the light receiving part of the optical fiber F 2 b and return to the branching part 3 through the optical rectifier 4.
- the reference light split at the branch unit 3 is transmitted by the optical fiber F 3, it is reflected by the reference mirror 9 returns at the optical fiber F 3 to the branch unit 3.
- the observation light and the reference light cause an interference phenomenon that is an optical physical phenomenon to become interference light.
- the interference light is collected by the collimating lens L2, and is converted into an electrical signal by the photoelectric effect along the time axis by the light receiving element 10.
- FIG. 8 is a graph showing an outline of the relationship between time and frequency obtained as an electrical signal by the light receiving element 10. The horizontal axis represents time and the vertical axis represents frequency.
- FIG. 7 is a graph showing an outline of the relationship between the depth distance and the scattering intensity axis obtained by Fourier transform.
- the depth distance is a distance in the straight direction of the observation light with the surface of the subject taken as zero along the Z axis in FIG.
- the scattered intensity value is stored in the computer 12 as float data which is, for example, a 4-byte single precision floating point real number (7 significant digits).
- the obtained float data is converted into an 8-bit gray scale of 256 gradations. This is to visualize the scattered intensity value.
- the gray scale can be a gradation value in 256 steps from 0 to 255.
- the present invention is not limited to 256 gradations, and can be implemented with other gradations.
- the conversion of float data into gradation values can be performed using, for example, commercially available software Labview (manufactured by National Instruments), but the software to be used is not limited.
- a person skilled in the art can arbitrarily set the scale for converting the float data into the gradation value. Depending on the set scale, the color tone and contrast may change, and the resulting image may change.
- a person skilled in the art can set the scale according to the purpose.
- Such gradation value data can also be stored in the computer 12.
- a color image can be obtained by a similar method by using a color scale when converting the scattering intensity value into a gradation value.
- Fig. 8 shows an outline of profiling waveform data and converting it into a computerized matrix state.
- the quantity relationship (A) obtained by the Fourier transform is stored in a state of a column 401 (B) including 16 pixels in one column.
- B a state of a column including 16 pixels in one column.
- Each pixel is assigned a gradation value of 0 to 255.
- Each pixel in (B) is assigned a gradation value corresponding to a scattering intensity value at a depth distance along the Z-axis, that is, a gradation value in each depth (Depth) of the graph in (A).
- the (C) matrix (matrix) 402 serving as the basis of the tomographic image can be completed.
- FIG. 9 shows conversion from (A) matrix to (B) two-dimensional optical coherence tomographic image.
- the two-dimensional optical coherence tomographic image is a gradation value converted from the scattering intensity value of the matrix 402 and is directly expressed as black and white shading.
- this description has been given by taking a 16-row ⁇ 28-column matrix (matrix) 402 as an example.
- the two-dimensional optical coherence tomographic image shown in FIG. 024 pixels (rows) ⁇ 512 pixels (columns). All of these operations are performed by the computer unit 12, and the image shown in FIG. 9B can be displayed on the display unit 14.
- the two-dimensional optical coherence tomographic image shown in FIG. 9B represents the tomogram cut at aa in FIG.
- FIG. 10 is a two-dimensional optical coherence tomographic image obtained as described above, which is a two-dimensional optical coherence tomographic image for use in extraction and quantification of the plaque region.
- region 205 are recognized.
- the gradation values in the respective portions can be, for example, an average of 169.4 (140 to 207) in the plaque region 202 and an average of 95.9 (63 to 119) in the enamel region 203. Using this value, the plaque area can be automatically extracted by the computer.
- a portion having a gradation value of 140 to 207 can be extracted as a dental plaque region.
- Such an operation can be performed by software configuring the measurement unit 13.
- the gradation value of each part is not strictly limited to the above range, and for example, a plaque portion region having a gradation value of 141 to 208 can be extracted.
- the gradation value of the dental plaque region can be designated in advance, and the judgment of the dentist or the operator does not intervene every measurement.
- the method of designation is to obtain a scattered intensity value or a gradation value by using an OCT apparatus before and after removing the plaque of a subject whose plaque is clearly recognized by diagnosis of a dentist. Compare these, and the scattered intensity value or gradation value before the removal of plaque in the part where the scattered intensity value or gradation value changed after removing the plaque, the scattering intensity value for specifying the plaque area Or it can be a gradation value.
- a three-dimensional image can be obtained from a plurality of two-dimensional optical coherence tomographic image data using software by a volume rendering technique.
- FIG. 11 shows a three-dimensional image obtained from a plurality of two-dimensional optical coherence tomographic images including FIG. Note that FIG. 11 is preferably capable of color display in the present embodiment.
- scanning in the X-axis direction in FIG. 3B is performed to obtain, for example, two-dimensional optical coherence tomographic image data of about 200 to 300 slice planes.
- Examples of software that can be used for volume rendering include AVIZO (manufactured by Visual Sciences Group), but are not limited thereto.
- the plaque region, enamel region, dentin region, and gingival region can be recognized in the entire region. Similar to the two-dimensional optical coherence tomographic image, the average values of the enamel of the dental tissue in which plaque is deposited and the scattering intensity of the plaque are different in the three-dimensional optical coherence tomographic image. Therefore, using the optical physical phenomenon, the three-dimensional region extraction of the plaque region is automatically performed using a computer without human intervention. That is, a voxel on a three-dimensional optical coherence tomographic image having a specific scattering intensity value can be obtained without setting a value for extraction by a person (physician or operator of the apparatus) between measurement and extraction. It can be extracted as a plaque region.
- the minimum value of the region width average 22.8 (range of the minimum value: 21.00 to 24.31)
- the maximum value of the region width can be an average of 39.10 (maximum value range: 37.29 to 40.89). Note that such setting of the region width can be appropriately performed by those skilled in the art while comparing the result with a conventionally known staining method, and is not limited to this range.
- the extracted plaque region can be displayed on the display unit 14 as an image, for example, as shown in FIG. Note that FIG. 12 can also preferably be displayed in color in this embodiment.
- Plaque quantification should be performed on plaque thickness, plaque length, plaque cross-sectional area, plaque volume, and plaque surface area, and / or any combination of these. Can do.
- plaque thickness in real space Reference value ( ⁇ m / pixel) for obtaining the thickness of the object with the OCT device x Thickness of the extracted plaque area (pixel) x 1 / k (1)
- the reference value ( ⁇ m / pixel) when the thickness of the object is obtained by the OCT apparatus is the length per pixel on the two-dimensional optical coherence tomographic image.
- the length in the X-axis direction and the length in the Y-axis direction are displayed as they are. It is known that the length (depth distance) in the Z-axis direction is displayed in an expanded state from the actual size depending on the refractive index k of the subject.
- the thickness reference value in the equation (1) is the length per pixel when it is expressed by k times the actual size and displayed on the two-dimensional optical coherence tomographic image. Therefore, in order to obtain the actual depth distance, it is necessary to multiply the number of extracted pixels and divide the display value on the two-dimensional optical coherence tomographic image by k.
- the refractive index of the subject can be set to k.
- the main components of standard plaque are insoluble glucan and mutan, which also contain oral bacteria and sugars.
- the refractive index k of the plaque may vary depending on the components constituting the plaque and the moisture content of the plaque.
- the coefficient k can be set to about 1.30 to 1.40. However, it is not limited to these ranges. In some cases, the coefficient k may be 1.1 to 2.0 or more.
- k can be determined from the value measured for the refractive index of plaque, or the average value is obtained from the values measured for the refractive index of plaque in multiple patients, and k is determined.
- the refractive index of dental plaque can be measured with a refractometer.
- the reference value ( ⁇ m / pixel) for obtaining the thickness of the object with the OCT apparatus can be obtained in advance by an object having a known thickness (length in the Z-axis direction) and refractive index k. .
- the thickness of the object A in the refractive index k a a thickness of 1mm in the real space, since in a two-dimensional optical interference tomographic image represented by 1 ⁇ k a (mm), the 1000 ⁇ k a ([mu] m ) Divided by the pixel count P a1 (pixel) of the thickness of the object A actually extracted on the two-dimensional optical coherence tomographic image.
- Such a reference value is calculated once by an OCT apparatus or by software, and thereafter, the same value can be used.
- the actual plaque thickness in the subject 200 can be calculated by the following equation (2).
- Pi represents the depth distance of the plaque region on the two-dimensional optical coherence tomographic image
- P represents the thickness (actual size) of the plaque.
- the coefficient k for deriving the actual size of the plaque thickness is a coefficient for calibrating the depth distance on the two-dimensional optical coherence tomographic image resulting from the difference between the refractive index of the subject and the air refractive index. The same value as in the above method can be used.
- the Pi value can be obtained from the two-dimensional optical coherence tomographic image shown in FIG. 10 and the P value can be calculated.
- the calculation (extraction) of the value of Pi and the calculation of the P value can be performed by software configuring the measurement unit 13.
- the thickness of the plaque may vary depending on the measurement location. The average thickness may be obtained by measuring at a plurality of measurement locations to obtain the plaque thickness, or the measured value at one location may be used as the plaque. The thickness may be as follows. Further, the thickness of plaque can be measured by other methods, and is not limited to this method.
- the plaque length refers to the length on the surface formed by the X and Y axes when the X, Y, and Z axes are set as shown in FIG.
- the length in the X-axis direction and the length in the Y-axis direction are displayed exactly as they are, and the plaque length in real space can be expressed by the following formula (3).
- Plaque length in real space Reference value ( ⁇ m / pixel) for obtaining the length of the object with the OCT device x length of the extracted plaque area (pixel) (3)
- the surface area of plaque is the surface area of the plaque surface that comes into contact with the air in three dimensions and the plaque surface that adheres to the tooth surface, and is the surface area of the plaque portion region having a curvilinear curve.
- the plaque region on the three-dimensional tomographic image is extracted as in the case of the volume.
- the surface area (polygon area) of the extracted plaque area is counted.
- the plaque surface area in real space can be obtained by the following equation (6).
- Real space plaque surface area Reference value ( ⁇ m 2 / polygon area) for obtaining the surface area of the target with the OCT device ⁇ extracted plaque area surface area (polygon area) (6)
- the reference value ( ⁇ m 2 / polygon area) for determining the surface area of the object with the OCT apparatus is determined as follows.
- the surface area of the object A having a surface area of 1 mm 2 in the real space is also expressed as 1 mm 2 on the three-dimensional optical coherence tomographic image.
- the extracted plaque area on the three-dimensional optical coherence tomographic image has a depth direction distance larger than that of real space plaque, but in terms of surface area, compared to thickness, cross-sectional area, and volume, There is no big difference between real space and optical coherence tomographic image.
- the above method mainly calculates the area of one reference pixel and the volume of one voxel, counts the number of pixels and the number of voxels in the extraction range on a computer, and obtains the cross-sectional area and volume of the extraction range. It is.
- a method for obtaining the ratio of the extracted region to the entire scan range and obtaining the area or volume of the extracted region in the real space is also possible. It is not limited to the method shown.
- one or more quantified values selected from plaque thickness, plaque length, plaque cross-sectional area, plaque surface area, and plaque volume. And a step of displaying the quantified value as one or more selected from an image, a table, and a graph over time.
- the method may further include a step of calculating a change amount of one or more quantified values of the plaque over time and displaying the change over time as either a numerical value, a two-dimensional image, or a three-dimensional image. preferable.
- Such an operation can be performed by using an appropriate data storage and data display system on a computer. Databases containing data over time can be particularly useful in aspects of oral hygiene management such as plaque control, periodontal disease treatment, caries risk reduction treatment.
- the plaque measurement and display method it is possible to display and quantify the plaque image by a non-invasive and safe method.
- This embodiment is the first application of the advantage of obtaining information in the depth direction of an OCT apparatus to plaque measurement.
- the OCT device is very useful in measuring what adheres to the surface of an object with a thickness of approximately 0.5 mm or less, such as plaque, and it has not been possible until now, and objective quantification of plaque. Realized.
- the image display and numerical calculation according to the above description can be obtained in about 30 to 180 seconds after irradiation with infrared light.
- the obtained data can be stored and made into a database, it is useful not only for collecting treatment information of individuals over time but also for collecting statistical data of dental patient populations. It can also be useful. Such quantification of plaque has not been realized so far, and it can be expected to be very useful in future dental clinical settings.
- the present invention relates to software for use in the plaque measurement and display method.
- the software for use in the plaque measurement and display method may constitute the computer unit 12 and the measurement unit 13 together with a computer that is a hardware resource, and the computer unit 12 and the measurement unit 13 described above.
- the steps performed in the above are extraction of plaque area, imaging of plaque area, and calculation of thickness, length, cross-sectional area, surface area and / or volume of plaque area. is there.
- the software in the present embodiment is software for causing a computer to execute a plaque measurement and display method, and a step of obtaining an optical coherence tomographic image based on the scattering intensity value of interference light obtained by the method described above.
- a step of extracting a plaque part region based on the optical coherence tomographic image a step of imaging the plaque part region, and a step of quantifying the plaque part region.
- the steps of extracting the plaque area include a step of storing the electrical signal of the scattered intensity value transmitted from the preamplifier 11 as data based on the interference light, a step of converting the scattered intensity value into a gradation value, and a step from the gradation value to the tooth. Extracting the plaque area. Which gradation value is to be used as the plaque region can be specified in advance, and it is not necessary for the dentist to manually specify the range for each measurement operation. Two-dimensional optical interference is performed by performing a plurality of filtering processes on part or all of the two-dimensional optical coherence tomographic image and the three-dimensional optical coherence tomographic image before the step of extracting the plaque region from the gradation value.
- Such a morphological identification step is used to identify each part displayed on the OCT image together with the scattering intensity value and the gradation value.
- the dentist looks at the OCT image, the relative positional relationship and the form of each part are visually confirmed, and each part on the image is identified based on the anatomical knowledge of the dentist.
- a process can be performed by form recognition by software.
- morphological features can be recognized and identified based on anatomical facts on the plaque region, gingival region, and enamel region on the image. And optionally, it can be displayed in different colors.
- Such an identification process can be performed before the process of extracting the plaque region.
- the method further includes a step of displaying each part in a different color on the two-dimensional optical coherence tomographic image and / or the three-dimensional optical coherence tomographic image for each part identified morphologically.
- the step of extracting the plaque region is performed in association with imaging conditions when imaging using the plaque measurement probe 8, and the extracted tooth Based on the plaque area, further comprising obtaining one or more quantified values selected from plaque thickness, plaque length, plaque volume, plaque cross-sectional area, plaque surface area Preferably it is done.
- the step of imaging the plaque region includes a step of forming a two-dimensional optical coherence tomographic image of the plaque portion region, a step of forming a three-dimensional optical coherence tomographic image of the plaque portion region, or both of them. May be.
- the process of imaging the dental plaque region into a three-dimensional optical coherence tomography can be performed by using a volume rendering prescription recognized by existing open sources.
- each value of plaque thickness, length, cross-sectional area, volume, and / or surface area is calculated.
- the calculation method may be the one shown in the above embodiment, but is not limited thereto.
- these quantitative values can be calculated by various technologies.
- the numerical values necessary for the calculation are the process of measuring a specific length or distance on the image displayed data, the image It can be obtained by a process of extracting the number of displayed pixels and the number of voxels.
- the software according to the present embodiment includes a step of creating a database of values obtained in the step of quantifying the plaque area, and the quantified value as one or more selected from an image, a table, and a graph, And causing the computer to execute a method that further includes the step of automatically displaying.
- the database of quantitative values, the display of images, tables or graphs, and / or the display over time can be implemented using known techniques.
- plaque can be extracted, imaged, and quantified by using it together with hardware resources in an arbitrary computer, and further, database creation and the like can be performed.
- the present invention relates to a method for measuring and displaying gingiva and / or alveolar bone.
- the same OCT apparatus as described in the first embodiment can also be used in the measurement and display method for gingiva and / or alveolar bone.
- the infrared rays are irradiated on the teeth and periodontal tissue, and the scattering intensity value of the interference light from the gingiva and alveolar bone is obtained, and the two-dimensional optical coherence tomographic image and / or the three-dimensional optical coherence tomographic image are obtained. Obtainable.
- a two-dimensional optical coherence tomographic image and / or a three-dimensional optical coherent tomographic image are used. It is characterized by evaluating an alveolar bone region. Quantitative measurement of these is very useful in the prevention and treatment of periodontal disease, but has not been feasible until now.
- the gingival and / or alveolar bone region is distributed over a relatively wide range. Therefore, it is difficult to capture the whole image with an OCT image.
- the method for measuring and displaying gingiva and / or alveolar bone includes a step of dividing near-infrared light output from a light source into measurement light and reference light, and the measurement light is applied to teeth and periodontal tissue in the oral cavity.
- the step of obtaining interference light from the reflected light and backscattered light obtained from the teeth and periodontal tissue, and the reference light, and the scattering intensity value of the interference light Obtaining a coherent tomographic image, extracting a gingival and / or alveolar bone region having a specific scattering intensity value, quantifying the gingiva and / or alveolar bone, and gingiva and / or alveolar bone And quantifying the gingiva and / or alveolar bone over time to further obtain gingival swelling and / or change in alveolar bone.
- the process up to obtaining the optical coherence tomographic image based on the scattered light intensity value of the interference light is the same as in the first embodiment, and can be performed in the same manner. Obtainable.
- the step of extracting the gingival region is performed by designating a gradation value indicating the gingival region and extracting one having a specific gradation value, as in the other regions described in the first embodiment. Can do.
- the gradation value indicating the gingival region can be set to 119 to 142, for example.
- Such gradation values can be determined so that the contrast of the entire OCT image is most clinically consistent when the scattering intensity value obtained by the OCT measurement is converted.
- the step of quantifying the volume of the gingiva is similar to the quantification of the volume with the plaque, by calculating in advance the volume per voxel on the three-dimensional optical coherence tomographic image, The volume on the three-dimensional optical coherence tomographic image is obtained by counting the number of voxels in the extracted gingival region. Furthermore, by dividing this value by the calibration rate k of the OCT depth direction distance, the volume of the gingiva can be quantified.
- Gingival volume in real space Reference value (mm 3 / voxel) for obtaining the target volume with the OCT device ⁇ extracted gingival region volume (voxel) ⁇ 1 / k
- the area per pixel on the two-dimensional optical coherence tomographic image is calculated in advance, and the number of pixels in the gingival region extracted from the two-dimensional optical coherence tomographic image To obtain a cross-sectional area on the two-dimensional optical coherence tomographic image. Further, this value is divided by the calibration rate k of the OCT depth direction distance, thereby digitizing the gingival cross-sectional area.
- the formula is expressed below.
- the calibration rate k in this case can be determined based on the refractive index of the gingiva, similarly to the calibration rate k used for quantifying plaque.
- the volume and / or cross-sectional area of the gingiva is measured over time for the same patient, and the amount of change is obtained.
- swelling is present in the gingiva, in particular, a change in swelling can be obtained, but even if there is no swelling in the gingiva, it may be a measurement target.
- the quantified value and the amount of change it is possible to quantitatively evaluate whether or not there is swelling in the gingiva, or the condition of the gingiva due to the progress of treatment.
- the tone value indicating the alveolar bone region is designated and the one having a specific tone value is extracted in the same manner as the other regions and gingival region described in the first embodiment.
- the gradation value can be set to 45 to 70, for example.
- the method further includes a step of morphologically identifying the alveolar bone region on the optical coherence tomographic image based on anatomical facts before the step of extracting the alveolar bone region.
- Quantification of the volume and cross-sectional area of the alveolar bone can be performed in the same manner as the gingiva, and each is represented by the following formula.
- the coefficient k in this case can also be determined based on the refractive index of the alveolar bone.
- the coefficient k 1.38, which is the refractive index of a living body, can be approximately used.
- the coefficient k can be between 1.3 and 1.4, but is not limited thereto. In some cases, the coefficient k may be 1.1 to 2.0 or more.
- Volume of alveolar bone in real space Reference value (mm 3 / voxel) for obtaining the target volume with the OCT device ⁇ volume of the extracted alveolar bone region (voxel) ⁇ 1 / k
- Cross section of alveolar bone in real space Reference value (mm 2 / pixel) for obtaining the cross-sectional area of the object with the OCT device x cross-sectional area of the extracted alveolar bone region (pixel) / x 1 / k
- the volume and cross-sectional area of the alveolar bone in the real space obtained as described above are measured over time, and the change is recorded. Since gingivitis may involve destruction of alveolar bone, a decrease in the quantitative value of alveolar bone suggests progression of gingivitis. By obtaining such a value quantitatively and with time, it becomes easier to monitor the medical condition.
- the step of imaging the gingiva and / or alveolar bone is performed by distinguishing the gingival region and / or alveolar bone from the plaque region and enamel region in the two-dimensional optical coherence tomographic image or the three-dimensional optical coherence tomographic image. Regions can be colored and shown as required.
- the gingival and / or alveolar bone measurement and display method and apparatus it is possible to quantitatively grasp the biological state directly connected to the pathology of gingivitis, which can greatly contribute to dental treatment.
- Table 3 shows the measurement results of the gingival area tone values.
- Table 4 shows the gradation value measurement results of the alveolar bone region.
- the calibration rate of the OCT depth direction distance based on the refractive index of plaque was 1.35.
- Example 2 As shown in Example 1, the plaque area on the two-dimensional tomographic image was extracted from the fact that the gradation value of the plaque area was different from that of the enamel area. Thereafter, the thickness, length, and cross-sectional area (pixel) of the extracted plaque area were counted. Photoshop cs5 (made by adobe (registered trademark)) was used for the analysis of the two-dimensional optical coherence tomographic image.
- Table 6 shows the thickness, length, and cross-sectional area of the obtained plaque. Cases 1 to 10 correspond to cases 1 to 10 of Example 1.
- the upper table results show values in OCT space (pixels), and the lower table results show values in real space (meters).
- the minimum value of the region width average 22.8 (range of the minimum value: 21.00 to 24.31), the maximum value of the region width: average 39.10 (range of the maximum value: 37.29 to 40.31).
- Table 3 shows the extraction results of the plaque area based on the plaque staining method. Cases 1 to 10 correspond to cases 1 to 10 of Examples 1 and 2.
- a reference for determining the volume and surface area of an object (plaque) with an OCT apparatus was created in advance.
- a polymer material after polymerization having a rectangular parallelepiped shape with dimensions of 5 ⁇ 5 ⁇ 1 mm was subjected to OCT imaging, and a volume (voxel) and a surface area (area) on a two-dimensional optical coherence tomographic image were obtained.
- AVIZO manufactured by Visual Sciences Group
- Example 2 As shown in Example 1, the plaque area on the three-dimensional tomographic image was extracted from the fact that the gradation value of the plaque area was different from that of the enamel area. Thereafter, the volume (voxel) and surface area of the extracted plaque area were counted. AVIZO (manufactured by Visual Sciences Group) was used for the analysis of the three-dimensional optical coherence tomographic image.
- the following formula was used for the measurement of the surface area.
- Real space plaque surface area (Criteria for determining the target surface area with the OCT device) x Surface area (polygon area)
- Table 10 below shows the gingival cross-sectional areas determined using the OCT apparatus.
- the alveolar bone region was extracted from the two-dimensional optical coherence tomographic image, and the cross-sectional area (pixel) of the extracted alveolar bone region was obtained on the OCT image.
- the refractive index of the alveolar bone changes depending on the blood flow volume in the alveolar bone or the like, it is considered that it approximates the biorefractive index (ne ⁇ 1.38).
- the calibration rate k is set to 1.38.
- Alveolar bone cross-sectional area in real space (Criteria for obtaining the cross-sectional area of an object with an OCT device) x cross-sectional area (pixel) / x 1 / 1.38
- the cross-sectional area of the alveolar bone obtained using the OCT apparatus is shown in Table 11 below.
- plaque image dyed by the conventional staining method was compared with the plaque imaging image extracted by the method according to the present invention and displayed quantitatively.
- O'leary's Plaque Control Record 0.5 mL of Dent Plaque Tester Liquid Co., Ltd. Lion (product name, manufacturer) was used as a staining solution to stain the front teeth as the subject.
- FIG. 15A shows the result of taking a photograph of the stained plaque.
- FIG. 15B shows a plaque imaging image in which the plaque region is extracted and quantitatively displayed. It was found that the present invention enables plaque measurement that can sufficiently reflect the results of the staining method even when compared with the staining method that is the gold standard in medical practice in Japan.
- FIGS. 15A and 15B are color images.
- FIG. 16A shows an optical coherence tomographic image capturing the deposition of subgingival plaque.
- FIG. 16B is a schematic diagram of plaque deposition based on the image of FIG. In FIG. 16A, the plaque 202 is clearly recognized.
- FIG. 16B schematically shows the gingival margin plaque 206 and the subgingival margin plaque 207 between the enamel 203 and the gingiva 205. According to the present invention, it has been found that objective and quantitative measurement of subgingival plaque deposition, which has been impossible until now, can be performed.
- Plaque is a major cause of dental caries and periodontal disease, which are two major diseases of dentistry.In addition, it has entered an aging society and is not limited to dentistry, and systemic diseases such as aspiration pneumonia and infective endocarditis. It is the cause of the disease.
- This method is capable of imaging and quantifying plaque adhesion, which has not conventionally had an objective and quantitative evaluation method, and has the effect of leading to more reliable dental care.
- SYMBOLS 100 Dental plaque measurement display apparatus 1 Near-infrared light source 3 Branch part 4 Optical rectifier 5 Optical modification part 6 Polarization and attenuation board 8 Plaque measurement probe 9 Reference mirror 10 Light receiving element 11 Preamplifier 12 Computer part 13 Measurement part 14 Display part 15 Imaging position fixing occlusion block 81 Non-operating optical path control mirror 82 Active optical path control mirror 83 Objective lens 84 Plaque measurement probe tip 86 Imaging position adjustment stage 87a Imaging position adjustment X-axis control section 87b Imaging position adjustment Y-axis control unit 87c Shooting position adjustment Z-axis control unit 88a Shooting position adjustment ⁇ -axis control unit 88b Shooting position adjustment ⁇ -axis control unit 88c Shooting position adjustment ⁇ -axis control unit 89 Shooting position adjustment gonio-axis control unit 200 Subject (tooth) DESCRIPTION OF SYMBOLS 201 Air part area
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Abstract
Description
Control Record(PCR法)が導入されている。PCR法は、歯面を4面に分割し、その付着面数の総歯面数に対する割合を求め、口腔内清掃状態を評価する手法である。しかし、この方法は、有り、無しの二段階評価法であり、歯垢付着の状態把握に対する詳細性に欠ける。また、歯垢の染色操作自体が患者に強い不快感を与え、染色後の染色液の除去が煩雑である。さらに、歯垢以外の部分も染色されるため、検査法の特異度が低いなどの不都合も多い。よって、口腔内清掃の重要性の認識を普及させるために十分な方法とはいえない。
[客観性・普遍性]
従来、歯科臨床および歯科検診では、視診・触診などの主観的検査法が主体で値にばらつきがあった。しかし本発明により、歯垢、歯肉及び歯槽骨を客観的に定量化する評価法を提供することができる。本発明に係る方法及び装置では、画像上での歯垢部領域の抽出を、人の判断が介入することなく、コンピュータを用いて自動的に行うため、いずれの国、いずれの検査者が行っても同様のデータ取得ができ、再現性がよく、普遍的に使用可能である。
[画像化・数値化]
本発明に係る方法及び装置によれば、X線など従来の歯科画像診断機器では検出不可能であった歯垢の全層を2次元画像として評価することが可能である。特には、断層画像の評価が可能であるため、深さ方向の評価が可能となり、視診で確認不可能であった歯肉縁下の歯垢まで検出可能である。さらに、3次元画像化して歯垢の付着を評価可能であり、歯垢の厚さ、長さ、断面積、表面積、及び体積を画像化・数値化することが可能である。同様にこれまでに定量化の試みさえも行われていなかった歯肉及び歯槽骨についてまで、定量化が可能になった。
[定量化・データベース化]
本発明に係る方法及び装置は、定量的な測定が可能であるため、再現性・信頼性が高い。また、経時的な測定及び評価が可能である。画像化・数値化するため歯科検診に応用が可能であり、数値的なデータベースとして提供できる。
[安全性]
本発明に係る方法及び装置は、近赤外光を観察光として用いるため、従来の歯科レントゲン法では不可避であった、医療被曝をすることなく検査が可能である。さらに、非接触、非侵襲で行う検査法であるので、歯周組織の付着構造を破壊することなく、かつ細菌を周囲の歯周ポケットに播種することなく検査が可能である。
[信頼性、高感度・特異度]
本発明に係る方法及び装置において用いる近赤外光は、歯垢を形成するムタンやグルカンなどを透過し、歯質まで到達・描出可能である。歯垢の全層を画像化することができ、かつ、歯垢と歯質とを明確に区別しうるため、感度・特異度が高い信頼性の高い検査法である。
[インフォームドコンセントに有効]
歯垢は、歯面と類似した色調を有しており、う蝕、歯周病といった疾患は、初期に自覚症状が乏しいため、早期対応が十分ではないことが問題とされてきた。本発明に係る方法及び装置によれば、明確に歯垢沈着の有無を定量して評価でき、モチベーションの向上と疾患克服に期待できる。
本発明は、一実施形態によれば、歯垢計測表示装置である。本実施形態による歯垢計測表示装置は、OCT(Optical Coherent Tomography:OCT)装置を用いて、特に歯垢を選択的に計測するものである。ここで、OCT装置は、生体内組織をマイクロオーダーで極めて高解像度に測定可能な装置である。また、OCT装置では、体表面下にまで到達しうる近赤外線の光源を使用することで、被写体の表面部だけではなく深部までの測定が可能である。近赤外線は、レントゲン線(X線)のような生体に為害性がある電磁放射線ではないため、厳密に非侵襲な被写体の検査を行うことができる。本発明におけるOCT装置は、特にはフーリエドメインOCTである波長走査型OCT(Swept souce-OCT)であることが好ましい。
例えば歯間鼓形空隙の上部に歯垢測定用ファイバー型プローブ800を挿入する場合には、下方180度の回転とすることも可能であり、また例えば歯間鼓形空隙の下部に歯垢測定用ファイバー型プローブ800を挿入する場合には、上方180度の回転とすることも可能である。なお、シース806を歯間鼓形空隙内に固定させずに、プローブ本体801をシース806と共に前方又は後方に移動させて歯牙隣接面の画像を歯垢測定用ファイバー型プローブ800で撮影することも可能である。このような場合は、プローブ本体801をシース806内にて前後に移動させる移動手段を設けずに、シース806を移動させるシース移動手段を設けることができる。また、シース806を外側シースと内側シースとから形成される二重構成にして、歯間鼓形空隙内にて該外側シースを固定させ、プローブ本体801を内側シースと共に前方又は後方に移動させて歯牙隣接面の画像を撮影することも可能である。
歯垢の厚さの定量化方法の一例について説明する。歯垢の厚さの定量化には、まず、図10で2次元光干渉断層画像上における、歯垢部領域を抽出し、抽出した領域のピクセル数をカウントする。かかるピクセル数と、予め求めておいた、2次元光干渉断層画像上における1ピクセルあたりの長さ(μm)とにより、2次元光干渉断層画像上における歯垢の厚さが得られる。これを係数kで割ることにより、実空間の歯垢の厚さが得られる。実空間の歯垢の厚さは、以下の式(1)で表すことができる。
実空間の歯垢の厚さ=
OCT装置にて対象の厚さを求める際の基準値(μm/pixel)×抽出された歯垢部領域の厚さ(pixel)×1/k (1)
OCT装置にて対象の厚さを求める際の基準値(μm/pixel)=1000ka×1/Pa1
歯垢の長さとは、図3に示すようにX軸、Y軸、Z軸を設定したとき、X軸とY軸で作られる表面上の長さをいう。X軸方向の長さ、Y軸方向の長さは原寸通りに表示され、実空間の歯垢長さは、以下の式(3)で表すことができる。
実空間の歯垢長さ=
OCT装置にて対象の長さを求める際の基準値(μm/pixel)×抽出された歯垢部領域の長さ(pixel) (3)
なわち、例えば、実空間上の長さが1mmの物体Aの長さは、屈折率によらず、2次元光干渉断層画像上でも1(mm)で表されるため、この1000(μm)を、2次元光干渉断層画像上で実際に抽出した物体Aの長さのピクセル数カウントPa2(pixel)で割ることにより、算出することができる。
OCT装置にて対象の長さを求める際の基準値(μm/pixel)=1000×1/Pa2
歯垢の断面積の測定においては、二次元光干渉断層画像上の歯垢部領域を抽出する。その後、抽出された歯垢部領域の断面積(pixel)をカウントする。断面積を測定する際に
は、歯垢の厚さの測定時と同様、Z軸方向の厚さ情報が必要になる。よって、上記歯垢の厚さを求める際に使用した係数kを用いて、校正を行うことにより、実空間での断面積を得ることができる。
実空間の歯垢の断面積は、以下の式(4)で表すことができる。
実空間の歯垢断面積=
OCT装置にて対象の断面積を求める際の基準値(μm2/pixel)×抽出された歯垢部領域の断面積(pixel)×1/k(4)
OCT装置にて対象の断面積を求める際の基準値(μm2/pixel)=
ka×106×1/Pa3
歯垢の体積の定量化においては、まず、3次元断層画像上の歯垢部領域を抽出する。その後、抽出された歯垢部領域の体積(voxel)をカウントする。体積を測定する際にも、歯垢の厚さの測定時と同様、Z軸方向の厚さ情報が必要になる。よって、上記歯垢の厚さを求める際に使用した係数kを用いて、校正を行うことにより、実空間での体積を得ることができる。実空間における歯垢体積は、以下の式(5)で求めることができる。
実空間の歯垢体積=
OCT装置にて対象の体積を求める際の基準値(μm3/voxel)×抽出された歯垢部領域の体積(voxel)×1/k (5)
OCT装置にて対象の体積を求める際の基準値(μm3/voxel)=
ka×109×1/Va
歯垢の表面積とは、立体的に空気と接する歯垢表面と歯面に付着する歯垢表面を合わせた表面積であり、曲線的なカーブを持った歯垢部領域の表面積である。表面積の定量化においても、体積の場合と同様に、3次元断層画像上の歯垢部領域を抽出する。そして、抽出された歯垢部領域の表面積(polygon area)をカウントする。実空間における歯垢表面積は、以下の式(6)で求めることができる。
実空間の歯垢断表面積=
OCT装置にて対象の表面積を求める際の基準値(μm2/polygon area)×抽出された歯垢部領域の表面積(polygon area) (6)
OCT装置にて対象の表面積を求める際の基準値(μm2/polygon area)=
1×106×1/Poa
上記歯垢の計測表示方法において用いるためのソフトウェアは、ハードウェア資源であるコンピュータとともに、電算部12及び計測部13を構成してもよいものあり、上記において説明した、電算部12及び計測部13において実施する工程である、歯垢部領域の抽出、歯垢部領域の画像化、及び歯垢部領域の、厚さ、長さ、断面積、表面積、及び/または体積の算出を行うものである。すなわち、本実施形態におけるソフトウェアは、コンピュータに歯垢の計測表示方法を実行させるためのソフトウェアであって、前述の方法で得られた干渉光の散乱強度値に基づき、光干渉断層画像を得る工程と、前記光干渉断層画像に基づいて歯垢部領域の抽出を行う工程と、歯垢部領域を画像化する工程と、歯垢部領域の定量化する工程とを含む方法を実行させるためのものである。これらの工程については、歯垢の計測表示方法に関する上記実施形態において実質的に説明しており、説明した工程をハードウェア資源であるコンピュータとともに実施するものである。以下にさらに詳細に説明する。
本発明は、また別の実施形態によれば、歯肉及び/または歯槽骨の計測表示方法に関する。歯肉及び/または歯槽骨の計測表示方法においても、第1実施形態において説明したのと同じ、OCT装置を使用することができる。OCT装置を使用して、歯牙及び歯周組織に赤外線を照射し、歯肉及び歯槽骨からの干渉光の散乱強度値を得て、2次元光干渉断層画像及び/または3次元光干渉断層画像を得ることができる。
歯肉部領域を抽出する工程は、第1実施形態において説明したほかの領域と同様に、歯肉部領域を示す諧調値を指定して、特定の諧調値をもつものを抽出することによって実施することができる。歯肉部領域を示す諧調値は、例えば、119~142とすることができる。このような諧調値は、OCT測定により得られた散乱強度値を変換する際に、最もOCT画像全体のコントラストが臨床的に一致するようにして決定することができる。なお、歯肉部領域を抽出する工程の前に、前記光干渉断層画像上の歯肉部領域を、解剖学的事実に基づいて形態学的に識別化する工程をさらに含むことが好ましい。この工程により、解剖学的事実に基づいて形態学的に識別化することにより、歯肉部領域の抽出をより容易かつ正確に実施することができる。
歯肉の体積を数値化する工程は、歯垢との体積の定量化と同様に、3次元光干渉断層画像上の1ボクセルあたりの体積を予め算出しておき、前記3次元光干渉断層画像から抽出した歯肉部領域のボクセル数を計数することにより3次元光干渉断層画像上の体積を得る。さらにこの値を、OCT深さ方向距離の校正率kで除することにより、歯肉の体積を数値化することができる。端的に式で表すと以下のようになる。
実空間の歯肉の体積=
OCT装置にて対象の体積を求める際の基準値(mm3/voxel)×抽出された歯肉部領域の体積(voxel)×1/k
実空間の歯肉の断面積=
OCT装置にて対象の断面積を求める際の基準値(mm2/pixel)×抽出された歯肉部領域の断面積(pixel)/×1/k
次に、歯槽骨の数値化について説明する。歯槽骨部領域を抽出する工程は、第1実施形態において説明したほかの領域や歯肉部領域と同様に、歯槽骨部領域を示す諧調値を指定して、特定の諧調値をもつものを抽出することによって実施することができる。諧調値は、例えば、45~70とすることができる。歯槽骨部領域を抽出する工程の前に、前記光干渉断層画像上の歯槽骨部領域を、解剖学的事実に基づいて形態学的に識別化する工程をさらに含むことが好ましい。
OCT装置にて対象の体積を求める際の基準値(mm3/voxel)×抽出された歯槽骨部領域の体積(voxel)×1/k
実空間の歯槽骨の断面積=
OCT装置にて対象の断面積を求める際の基準値(mm2/pixel)×抽出された歯槽骨部領域の断面積(pixel)/×1/k
光源として、生体に無害な近赤外光光源を用い、図2に示す歯垢計測用プローブを用い、患者の前歯を被写体として撮影した。画像ソフトウェアphotoshop(Adobe社製)にて、被写体の散乱強度値を諧調値に変換して作成された2次元断層像の歯垢部領域とエナメル質部領域のそれぞれ150部位の階調値を測定した。その結果、エナメル質部領域の階調値と歯垢部領域の階調値が異なることを確認した。
<階調値>
歯垢部領域: 平均169.4(最大値207~最小値140)
エナメル質部領域: 平均95.9(最大値119~最小値63)
(Welchのt検定にて有意差を認めた。 **P<0.01)
<散乱強度値>
歯垢: 平均30(最大値39~最小値24)
エナメル質: 平均13(最大値16~最小値-4)
歯垢部領域とエナメル質部領域の階調値測定結果を表1及び表2に示す。
歯肉部領域: 平均133.1(最大値142~最小値119)
歯槽骨部領域: 平均56.8(最大値45~最小値70)
<実施の方法1>
本実施例では、OCT装置にて対象(歯垢)の厚さ、長さ及び断面積を求める際の基準を予め作成した。実空間にて、寸法が、5×5×1mmの直方体形態を有する重合後の高分子材料をOCT撮影し、2次元光干渉断層画像上における厚さ(pixel)、長さ(pixel)、断面積(pixel)を得た。2次元光干渉断層画像の解析にはPhotoshop cs5 (adobe(登録商標))を用いた。
1.65mm/86pixel= 0.0192…mm/pixel (19.2μm/pixel)
OCT装置にて対象の長さを求める際の基準は、以下の通りに得られた。
5mm/381pixel= 0.0131…mm/pixel (13.1μm/pixel)
OCT装置にて対象の断面積を求める際の基準は、以下の通りに得られた。
8.25mm2/32766pixel =0.000251785… mm2/pixel (約250μm2/pixel)
本実施例において、歯垢の屈折率に基づくOCT深さ方向距離の校正率は、1.35とした。
実施例1に示すよう、歯垢部領域の諧調値がエナメル質部領域と異なる事実から、2次元断層画像上の歯垢部領域を抽出した。その後、抽出された歯垢部領域の厚さ、長さ、断面積(pixel)をカウントした。2次元光干渉断層画像の解析にはPhotoshop cs5 (adobe(登録商標)社製)を用いた。
実空間の歯垢厚さ=
(OCT装置にて対象の厚さを求める際の基準19.2μm/pixel)×厚さ(pixel)×1/k
長さの計測には以下の式を用いた。
実空間の歯垢長さ=
(OCT装置にて対象の長さを求める際の基準13.1μm/pixel)×長さ(pixel)
断面積の計測には以下の式を用いた。
実空間の歯垢断面積=
(OCT装置にて対象の断面積を求める際の基準250μm2/pixel)×断面積(pixel)×1/k
得られた歯垢の厚さ、長さ、断面積を表6に示す。症例1~10は、実施例1の症例1~10に対応する。表上段結果はOCT空間上の値(pixel)を示し、表下段結果は実空
間における値(メートル)を示す。
まず、2次元データの3次元化を行った。干渉光をコンピュータにより自動計算処理して得られたfloatデータをソフトウェアAVIZO(Visual Sciences Group社製)に取り込み、ボリュームレンダリングにて3次元画像を作製した。次に、ソフトAVIZO上で歯垢部領域の任意の1ボクセルを選択した。歯垢染出し写真と同等の領域が選択されるように領域幅を調整(散乱強度値の最小値と最大値を調節)する方法でAVIZO上において歯垢部領域を抽出した。
<実施の方法1>
本実施例では、OCT装置にて対象(歯垢)の体積、表面積を求める際の基準を予め作成した。実空間にて、寸法5×5×1mmの直方体形態を有する重合後の高分子材料をOCT撮影し、2次元光干渉断層画像上における体積(voxel)、表面積(area)を得た。3次元光干渉断層画像の解析にはAVIZO(Visual Sciences Group社製)を用いた。
OCT装置にて対象の体積を求める際の基準値:
41.25mm3/90745512 voxel=0.0000004545…mm3/ voxel(約454.5μm3/ voxel)
OCT装置にて対象の表面積を求める際の基準値:
83mm2/2325298 polygon area=0.00003569… mm2/ polygon area(約35.7μm2/polygon area)
歯垢の屈折率に基づくOCT深さ方向距離の校正率:k=1.35
実施例1に示すよう、歯垢部領域の諧調値がエナメル質部領域と異なる事実から、3次元断層画像上の歯垢部領域を抽出した。その後、抽出された歯垢部領域の体積(voxel)、表面積(area)をカウントした。3次元光干渉断層画像の解析にはAVIZO(Visual Sciences Group社製)を用いた。
実空間の歯垢体積=
(OCT装置にて対象の体積を求める際の基準)×体積(voxel)×1/k(k=1.35)
表面積の計測には以下の式を用いた。
実空間の歯垢断表面積=
(OCT装置にて対象の表面積を求める際の基準)×表面積(polygon area)
(1)歯肉の定量化
2次元光干渉断層画像より、歯肉部領域を抽出し、抽出された歯肉部領域の断面積(pixel)をOCT画像上で求めた。実空間に比較しOCT画像における歯肉部領域は、深さ方
向に拡大しているため屈折率に基づき校正して実空間の歯肉の断面積を求めた。係数kは、1.38を用いた。正確には炎症や性状の程度により歯肉の屈折率は変化するが、生体屈折率(ne≒1.38)と近似すると考え、本実施例においては校正率kを1.38とした。
実空間の歯肉断面積=
(OCT装置にて対象の断面積を求める際の基準)×断面積(pixel)/× 1/1.38
2次元光干渉断層画像より、歯槽骨部領域を抽出し、抽出された歯槽骨部領域の断面積(pixel)をOCT画像上で求めた。実空間に比較しOCT画像における歯槽骨部領域は、
深さ方向に拡大しているため屈折率に基づき、校正して実空間の歯槽骨の断面積を求めた。k=1.38とした。なお、正確には歯槽骨内の血流量などにより歯槽骨の屈折率は変化するが、生体屈折率(ne≒1.38)と近似すると考え、本実施例においては校正率kを1.38とした。
実空間の歯槽骨断面積=
(OCT装置にて対象の断面積を求める際の基準)×断面積(pixel)/× 1/1.38
従来の染色法により染めだした歯垢画像と、本発明に係る方法で抽出し、定量的に表示した歯垢イメージング画像とを比較した。O’learyのPlaque Control Recordに従って、染色液として、デント プラークテスター リキッド 株式会社ライオン(製品名、製造元)を0.5mL用いて、被写体である前歯を染色した。染め出した歯垢について、写真を撮った結果が、図15(A)である。
別の被写体について、本発明の装置及び方法を用いて、2次元断層画像を得た。歯垢部領域抽出領域の設定は、実施例2と同様とした。スキャン範囲は、歯肉縁より3mm程度下部まで範囲に含まれるように設定した。図16(A)に、歯肉縁下歯垢の沈着を捉えた光干渉断層画像を示す。図16(B)は、図16(A)の画像に基づく歯垢沈着の模式図である。図16(A)には、歯垢202が明らかに認められる。図16(B)は、エナメル質203と歯肉205のあいだに、歯肉縁上歯垢206、歯肉縁下歯垢207を模式的に表示している。本発明によって、これまで不可能であった歯肉縁下の歯垢沈着の客観的かつ定量的に計測する事が可能であるがわかった。
1 近赤外光源
3 分岐部
4 光整流器
5 光修飾部
6 偏光および減衰板
8 歯垢計測用プローブ
9 参照ミラー
10 受光素子
11 プリアンプ
12 電算部
13 計測部
14 表示部
15 撮影位置固定用咬合ブロック
81 非稼働式光路制御鏡
82 稼働式光路制御鏡
83 対物レンズ
84 歯垢計測用プローブ先端部
86 撮影位置調整用ステージ
87a 撮影位置調整用X軸制御部
87b 撮影位置調整用Y軸制御部
87c 撮影位置調整用Z軸制御部
88a 撮影位置調整用α軸制御部
88b 撮影位置調整用β軸制御部
88c 撮影位置調整用γ軸制御部
89 撮影位置調整用ゴニオ軸制御部
200 被写体(歯牙)
201 空気部領域
202 歯垢部領域
203 エナメル質部領域
204 象牙質部領域
205 歯肉部領域
206 歯肉縁上歯垢
207 歯肉縁下歯垢
301 計測可能野
302 測定光の軌道模式
303 歯軸
304 測定光の向きに平行な軸
α 測定角(不適正)
R 適正範囲内の測定角
305 歯面との平行線
β 不適切範囲の測定角
306 測定光の向きに平行な軸
401 散乱強度を1列に配置した1点分の行列状データ(マトリクス)
402 次波形に対しても同行程を順次繰りかえして得た1ライン分の行列状データ(マトリクス)
F 光ファイバー
L コリメートレンズ
800 歯垢計測用ファイバー型プローブ
801 歯垢計測用ファイバー型プローブ本体
802 接続導光部
803 GRINレンズ
804 プリズム
805 回転手段
806 シース
Claims (17)
- 光源から出力された近赤外光を測定光と参照光に分割する工程と、
前記測定光を口腔内の歯牙に向けて照射しつつ掃引する工程と、
前記歯牙から得られた反射光および後方散乱光と、前記参照光とから干渉光を得る工程と、
前記干渉光の散乱強度値に基づき、光干渉断層画像を得る工程と、
前記光干渉断層画像から、特定の散乱強度値を有する歯垢部領域を抽出する工程と、
歯垢を定量化する工程と、
歯垢を画像化する工程と
を含む、歯垢の計測表示方法。 - 前記光干渉断層画像が、歯垢部領域と、歯垢が沈着するエナメル質部領域と、歯肉部領域とを区別して、2次元的に表示する2次元光干渉断層画像である、請求項1に記載の方法。
- 前記光干渉断層画像が、歯垢部領域と、歯垢が沈着するエナメル質部領域と、歯肉部領域とを区別して、3次元的に立体画像化して表示する3次元光干渉断層画像である、請求項1に記載の方法。
- 前記光干渉断層画像が、歯垢部領域と、歯垢が沈着するエナメル質部領域と、歯肉部領域とを区別して、2次元的に表示する2次元光干渉断層画像と、歯垢部領域と、歯垢が沈着するエナメル質部領域と、歯肉部領域とを区別して、3次元的に立体画像化して表示する3次元光干渉断層画像との両方である、請求項1に記載の方法。
- 前記歯垢を定量化する工程が、前記2次元光干渉断層画像から抽出した歯垢部領域から、歯垢の厚さ及び/または長さを数値化する工程を含む、請求項2または4に記載の方法。
- 前記歯垢を定量化する工程が、前記3次元光干渉断層画像から抽出した歯垢部領域から、歯垢の体積を数値化する工程を含む、請求項3または4に記載の方法。
- 前記歯垢を定量化する工程が、前記2次元光干渉断層画像または3次元光干渉断層画像から抽出した歯垢部領域から、歯垢の断面積を数値化する工程を含む、請求項2または4に記載の方法。
- 前記歯垢を定量化する工程が、前記3次元光干渉断層画像から抽出した歯垢部領域から、歯垢の表面積を数値化する工程を含む、請求項2または4に記載の方法。
- 前記歯垢を定量化する工程において得られる、歯垢の厚さ、歯垢の長さ、歯垢の体積、歯垢の断面積、歯垢の表面積から選択される一以上の定量した値をデータベース化する工程と、
前記定量した値を、画像、表、グラフから選択される一以上として、経時的に表示する工程と
をさらに含む、請求項1に記載の方法。 - 前記歯垢の厚さ、歯垢の長さ、歯垢の体積、歯垢の断面積、歯垢の表面積から選択される一以上の定量した値の変化量を経時的に算出し、数値、2次元画像、または3次元画像のいずれかとして、経時的に表示する工程をさらに含む、請求項9に記載の方法。
- 近赤外光を出力する光源と、
前記近赤外光を測定光と参照光に分割する分岐部と、
前記測定光を口腔内の歯牙に向けて照射しつつ掃引する歯垢測定プローブと、
前記歯牙から得られた反射光および後方散乱光と、前記参照光とから得られた干渉光を受信する受光素子と、
前記干渉光の散乱強度値を諧調値に変換し、光干渉断層画像を与える電算部と、
歯垢部領域を抽出し、歯垢の定量化を行う抽出および計測部と、
光干渉断層画像及び定量結果を表示する表示部と
を備える、歯垢の計測表示装置。 - コンピュータに歯垢の計測表示方法を実行させるためのソフトウェアであって、請求項1に記載の方法で得られた干渉光の散乱強度値に基づき、光干渉断層画像を得る工程と、
前記干渉光の散乱強度値に基づき、歯垢部領域の抽出を行う工程と、
前記歯垢部領域を画像化する工程と、
前記抽出した歯垢部領域に基づき、歯垢の厚さ、歯垢の長さ、歯垢の断面積、歯垢の体積、歯垢の表面積から選択される一以上の定量化した値を得る工程と
を含む方法をコンピュータに実行させるためのソフトウェア。 - 前記歯垢部領域の抽出を行う工程の前に、前記光干渉断層画像上の歯垢、歯肉、エナメル質を、解剖学的事実に基づいて形態学的に識別化する工程をさらに含む方法をコンピュータに実行させるための、請求項12に記載のソフトウェア。
- 前記定量化した値を得る工程において得られた値をデータベース化する工程と、
前記定量化した値を、画像、表、グラフから選択される一以上として、経時的に表示する工程と
をさらに含む方法をコンピュータに実行させるための、請求項12または13に記載のソフトウェア。 - 光源から出力された近赤外光を測定光と参照光に分割する工程と、
前記測定光を口腔内の歯牙及び歯周組織に向けて照射しつつ掃引する工程と、
前記歯牙及び歯周組織から得られた反射光および後方散乱光と、前記参照光とから干渉光を得る工程と、
前記干渉光の散乱強度値に基づき、光干渉断層画像を得る工程と、
特定の散乱強度値を有する歯肉及び/または歯槽骨部領域を抽出する工程と、
歯肉及び/または歯槽骨を定量化する工程と、
歯肉及び/または歯槽骨を画像化する工程と
を含み、
前記歯肉及び/または歯槽骨を定量化する工程を経時的に行うことにより、歯肉の腫脹及び/または歯槽骨の変化量を得る工程をさらに含む、歯肉及び/または歯槽骨の計測表示方法。 - 近赤外光を出力する光源と、
前記近赤外光を測定光と参照光に分割する分岐部と、
前記測定光を口腔内の歯牙及び歯周組織に向けて照射しつつ掃引する測定プローブと、
前記歯牙及び歯周組織から得られた反射光および後方散乱光と、前記参照光とから得られた干渉光を受信する受光素子と、
前記干渉光の散乱強度値を諧調値に変換し、光干渉断層画像を与える電算部と、
歯肉及び/または歯槽骨部領域を抽出し、歯肉及び/または歯槽骨の定量化を行う抽出および計測部と、
光干渉断層画像及び定量結果を表示する表示部と
を備える、歯肉及び/または歯槽骨の計測表示装置。 - コンピュータに歯肉及び/または歯槽骨の計測表示方法を実行させるためのソフトウェアであって、請求項15に記載の方法で得られた干渉光の散乱強度値に基づき、光干渉断層画像を得る工程と、
前記干渉光の散乱強度値に基づき、歯肉及び/または歯槽骨部領域の抽出を行う工程と、
前記歯肉部領域及び/または歯槽骨部領域を画像化する工程と、
前記抽出した歯肉部領域及び/または歯槽骨部領域に基づき、歯肉及び/または歯槽骨を定量化する工程と、
前記歯肉及び/または歯槽骨を定量化する工程を経時的に行うことにより、歯肉の腫脹及び/または歯槽骨の変化量を測定する工程と
を含む方法をコンピュータに実行させるためのソフトウェア。
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JP2014525810A JP6177777B2 (ja) | 2012-07-19 | 2013-07-12 | 歯垢、歯肉及び歯槽骨の計測表示方法及び計測表示装置 |
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US14/413,524 US9445724B2 (en) | 2012-07-19 | 2013-07-12 | Method and apparatus for measuring and displaying dental plaque |
US15/230,982 US10251558B2 (en) | 2012-07-19 | 2016-08-08 | Method and apparatus for measuring and displaying dental plaque, gingiva, and alveolar bone |
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US10251558B2 (en) | 2019-04-09 |
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JP6177777B2 (ja) | 2017-08-09 |
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