Caries detection device

Abstract

To achieve short-time detection of dental caries by detecting Raman scattering light.SOLUTION: A dental caries detection device (1) includes: a screening optical system (10A) that irradiates a tooth (T) with a near-infrared ray from a light source (11) to detect light transmitted through the tooth (T); and a Raman scattering light detection optical system (10B) that irradiates a dental caries candidate portion in the tooth (T) detected from information on the transmitted light with a near-infrared ray from the light source (11) to detect Raman scattering light generated from the dental caries candidate portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a caries detection device. [Background technology]

[0002] It is known that periodontal diseases such as "dental caries" and "periodontal disease" account for a large proportion of the causes of tooth loss. Focusing on "dental caries," which is one type of periodontal disease, a technique that uses Raman spectroscopy, a type of spectroscopic technology, is known as a technique for quantitatively evaluating the progression of "dental caries" (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-78978 [Patent Document 2] International Publication No. 2019 / 106819 [Patent Document 3] Special Publication No. 2018-521701 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Raman spectroscopy, the intensity of Raman scattered light is generally low. Therefore, to obtain a sufficient amount of light for quantitative evaluation, a long integration time is required. This leads to a long diagnosis time, and patients are forced to keep their mouths open for long periods of time, which causes great stress for them. Thus, conventional caries detection technologies that use Raman scattered light still have room for improvement in terms of shortening the time required for caries detection.

[0005] An object of one aspect of the present invention is to provide a technology that enables caries detection by detecting Raman scattered light in a short period of time. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one embodiment of the caries detection device of the present invention comprises a screening optical system that irradiates a tooth with a first test light from a light source and detects light transmitted through the tooth or fluorescence emitted from the tooth, and a Raman scattered light detection optical system that irradiates a caries suspected portion in the tooth identified from information on the transmitted light or fluorescence detected by the screening optical system with a second test light from the light source and detects Raman scattered light emitted from the caries suspected portion. [Effects of the Invention]

[0007] According to one aspect of the present invention, caries detection by detecting Raman scattered light can be achieved in a short time. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating the configuration of a caries detection device according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing an example of the functional configuration of a caries detection device according to a first embodiment of the present invention. [Figure 3] 4 is a flowchart showing an example of a process for caries detection according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram illustrating screening of a caries suspected part in the first embodiment of the present invention. [Figure 5] FIG. 1 is a photograph showing an example of an image showing a caries suspected site obtained by screening in the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram for explaining caries detection in the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing an example of a caries detection result in the first embodiment of the present invention. [Figure 8] FIG. 3 is a diagram schematically illustrating the configuration of a caries detection device according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a diagram illustrating screening of a caries suspected part in the second embodiment of the present invention. [Figure 10]FIG. 10 is a photograph showing an example of an image showing a caries suspected site obtained by screening in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment 1] An embodiment of the present invention will be described in detail below. A caries detection device in an embodiment of the present invention irradiates a tooth, which is a measurement object, with test light to acquire a transmitted light image or an image of fluorescence emitted from the tooth, and identifies a portion suspected of having caries. The caries detection device then irradiates the portion suspected of having caries with test light and detects Raman scattered light emitted from the portion. The embodiment of the present invention described below includes a system that drives the caries detection device.

[0010] [Device configuration] Fig. 1 is a diagram schematically showing the configuration of a caries detection device according to a first embodiment of the present invention. As shown in Fig. 1, the caries detection device 1 has a light source 11, a transmitted light receiving sensor 12, a Raman scattered light receiving sensor 13, an optical system 14, and a display device 15. The caries detection device 1 also has a control unit for controlling the operation of each of these units.

[0011] The light source 11 is a light source that generates inspection light in the near-infrared region (near-infrared light). As the light source 11, a high-output light source such as a semiconductor laser or a fiber laser can be used.

[0012] The transmitted light receiving sensor 12 is a sensor for detecting transmitted light that passes through the tooth T, which is an object to be measured and is irradiated with near-infrared light. In this embodiment, the transmitted light refers to the light that is transmitted through the tooth T out of the near-infrared light irradiated onto the tooth T. The transmitted light receiving sensor 12 can be an image sensor such as a CMOS (complementary metal-oxide semiconductor) camera or a CCD (charge-coupled device) camera, and in this embodiment, it is, for example, a CMOS camera.

[0013] The Raman scattered light receiving sensor 13 is a sensor for detecting Raman scattered light generated from the tooth T irradiated with near-infrared light. The Raman scattered light receiving sensor 13 can be an optical detection element such as a photodiode or a photomultiplier tube, and in this embodiment, it is, for example, a photodiode.

[0014] The optical system 14 is configured to form paths for the inspection light and transmitted light from the light source 11 to the transmitted light receiving sensor 12, and also to form paths for the inspection light and Raman scattered light from the light source 11 to the Raman scattered light receiving sensor 13. The optical system 14 can be configured by a combination of optical elements. The optical system 14 can be configured by an optical filter 141 and a variable focal length lens 142.

[0015] The optical filter 141 is an optical element that reflects near-infrared light from the light source 11 toward the tooth T and transmits Raman scattered light from the tooth T. The optical filter 141 can be an optical filter that reflects or transmits light of a specific wavelength, such as a band-pass filter, an edge filter, a long-pass filter, or a notch filter. In this embodiment, the optical filter 141 is, for example, a notch filter, an edge filter, or a long-pass filter.

[0016] The variable focal length lens 142 is an optical element that is positioned closer to the tooth T than the optical filter 141 and that changes the irradiation range on the tooth T of the near-infrared light that is irradiated onto the tooth T. The variable focal length lens 142 may have any optical configuration that allows the focal length to be changed, and may be a single optical element such as a liquid lens, or may be composed of multiple optical elements such as a lens unit that changes the focal length by changing the spacing between two or more lenses. In this embodiment, the variable focal length lens 142 will be described as a form in which a liquid lens is applied.

[0017] The optical system 14 may further include other optical devices such as optical fibers and various mirrors to configure the above-mentioned light path.

[0018] Here, the light source 11, the transmitted light receiving sensor 12, and the optical system 14 constitute an optical system that irradiates the tooth T with near-infrared light from the light source 11 and detects the light transmitted through the tooth T. In this embodiment, this optical system is also referred to as a screening optical system 10A. In this embodiment, the screening optical system 10A further includes a variable focal length lens 142, more specifically, for example a liquid lens, as a variable focal length optical system that can change the irradiation range of the near-infrared light on the tooth T.

[0019] Furthermore, the light source 11, the Raman scattered light receiving sensor 13, and the optical system 14 constitute an optical system that irradiates a caries suspected portion (described below) of the tooth T with near-infrared light from the light source 11 and detects Raman scattered light generated from the caries suspected portion. In this embodiment, this optical system is also referred to as the Raman scattered light detection optical system 10B. In this embodiment, the Raman scattered light detection optical system 10B further includes an optical filter 141 that transmits only light of a specific wavelength from the Raman scattered light generated from the caries suspected portion.

[0020] The display device 15 is a device for displaying one or both of an image based on information about transmitted light detected by the screening optical system 10A and an image based on information about Raman scattered light detected by the Raman scattered light detection optical system 10B. The "image based on information about detected light" may be any image that can be visually recognized as the relevant information by a user of the caries detection device, and examples include an image of the tooth T, and a spectrum and graph showing the characteristics (intensity, wavelength, etc.) of the detected light. The display device 15 is a device that visually outputs the above information, and is, for example, a liquid crystal display.

[0021] In this embodiment, the light source 11 is a device that outputs near-infrared light in both the screening optical system 10A and the Raman scattered light detection optical system 10B. That is, in this embodiment, the first inspection light in the screening optical system 10A and the second inspection light in the Raman scattered light detection optical system 10B are both near-infrared light.

[0022] In this embodiment, the light source 11, transmitted light receiving sensor 12, Raman scattered light receiving sensor 13, and optical system 14 are held in an inspection jig so that teeth T in the oral cavity can be inspected. The inspection jig is an instrument that can be inserted into a human oral cavity, and holds at least the transmitted light receiving sensor 12 and the variable focal length lens 142 so that teeth T in the oral cavity can be inspected, for example. In this embodiment, the inspection jig holds the transmitted light receiving sensor 12 on the back side of the oral cavity, with the teeth T in between, and holds the light source 11, optical system 14, and Raman scattered light receiving sensor 13 on the front side of the oral cavity.

[0023] [Functional configuration] 2 is a block diagram showing an example of the functional configuration of the caries detection device according to this embodiment. The caries detection device 1 further includes a control unit 16. The control unit 16 is, for example, a processor, and realizes the desired control by a program for functioning as a specific control block. As shown in FIG. 2, the control unit 16 includes a caries candidate portion identification unit 161, a caries detection unit 162, a focal length control unit 163, a display control unit 164, a second test light irradiation position correction unit 165, a shake correction unit 166, and a difference detection unit 167.

[0024] [Detection of dental caries] Caries detection using the caries detection device 1 may be performed by a user such as a dentist manually operating the caries detection device 1, or may be performed partially or entirely automatically by a control device. In the present embodiment, caries detection using the caries detection device 1 will be described below as an example in which control by a control device is used. Figure 3 is a flowchart showing an example of caries detection processing in this embodiment.

[0025] <Screening> The caries suspected part identifying unit 161 starts measurement for caries screening of the subject's tooth T (step S301). The screening is performed by irradiating the tooth T with near-infrared light. The control unit 16 causes the light source 11 to generate near-infrared light. The near-infrared light generated by the light source 11 is reflected by the optical filter 141, passes through the variable focal length lens 142, which is a liquid lens, and is then irradiated onto the tooth T.

[0026] 4 is a diagram for explaining screening of caries suspected portions in this embodiment. Near-infrared light passes through the enamel and dentin of the tooth T. Therefore, the transmitted light receiving sensor 12 receives and detects the transmitted near-infrared light.

[0027] In this way, for example, when near-infrared light is sequentially irradiated onto all of the teeth T of the subject, information on the near-infrared light transmitted through all of the teeth T of the subject is obtained as an image of the transmitted light through the teeth T. In this way, the caries suspected part identifying unit 161 acquires an image of the near-infrared light transmitted through the teeth T as an image for screening (step S302).

[0028] Next, the caries suspected part identifying unit 161 analyzes the image (step S303). Fig. 5 is a diagram showing a photograph showing an example of an image showing a caries suspected part by screening in this embodiment. The photograph shown in Fig. 5 is cited from Graham C. Jones, Robert. S. Jones and Daniel Fried, Proc. of SPIE, 5313, 17 (2004).

[0029] In a normal tooth T without caries, near-infrared light passes through the enamel or dentin. On the other hand, in a tooth T where a unique part such as a cavity or alteration exists in the enamel or dentin, as in the case of caries, near-infrared light is absorbed, reflected, or scattered by the unique part. Therefore, a part of the tooth T that is suspected of having caries (caries candidate part) is represented as a dark part in the image of the tooth T taken using transmitted near-infrared light, as shown in frame A1 in FIG. 5. Therefore, a dark part like the one in the photograph shown in FIG. 5 can be determined to be a caries candidate part. The caries candidate part identifying unit 161 identifies a caries candidate part according to the information on the transmitted light detected by the screening optical system 10A, for example, by determining whether or not there is a difference in brightness based on a predetermined threshold value.

[0030] <Detection of dental caries using Raman spectroscopy> Next, the caries detection unit 162 starts Raman spectroscopy (step S304). FIG. 6 is a diagram for explaining caries detection in this embodiment. First, the focal length control unit 163 controls the voltage applied to the liquid lens serving as the variable focal length lens 142 to focus near-infrared light from the light source 11 on the caries suspected portion determined by the caries suspected portion identifying unit 161 in the specific tooth T. The caries suspected portion is, for example, the dark portion within frame A1 in FIG. 5. In this way, the caries detection unit 162 focuses near-infrared light on the caries suspected portion and starts Raman spectroscopy.

[0031] Next, the caries detection unit 162 acquires a Raman spectrum (step S305). The caries suspected portion is a small portion of the tooth T, and near-infrared light from the light source 11 is concentrated and irradiated onto the caries suspected portion. Light including Raman scattered light generated in the caries suspected portion reaches the optical filter 141. Of the light, only the Raman scattered light passes through the optical filter 141. Therefore, a portion of the Raman scattered light generated in the caries suspected portion reaches the Raman scattered light receiving sensor 13 via the optical system 14 and is detected. Raman scattered light is usually weak light, but because the near-infrared inspection light is concentrated and irradiated onto the caries suspected portion, the Raman spectrum of the caries suspected portion can be acquired in a short time.

[0032] Next, the caries detection unit 162 analyzes the Raman spectrum (step S306). Fig. 7 is a diagram showing an example of the caries detection result in this embodiment. As shown in Fig. 7, the Raman scattered light from the tooth T is in the range of 900 to 1000 cm -1 , but the intensity of the Raman scattered light is clearly lower in the carious portion of the tooth T than in the normal portion of the tooth T. The caries detection unit 162 analyzes the Raman spectrum for each caries suspected portion by, for example, superimposing the individual Raman spectra as shown in FIG. 7 , or by comparing the intensity of a specific peak or the intensity ratio between multiple peaks.

[0033] Next, the caries detection unit 162 performs a caries diagnosis (step S307). The caries detection unit 162 determines that a caries suspected portion that satisfies specific requirements in the Raman spectrum is a caries. For example, the caries detection unit 162 determines whether or not a caries exists based on a predetermined threshold value of peak intensity. Alternatively, the caries detection unit 162 calculates the difference (or ratio) between the intensity of Raman scattered light in the caries suspected portion and the intensity of Raman scattered light in a normal portion, and determines whether or not a caries exists based on a predetermined threshold value for this difference or ratio. In this way, caries is detected in the caries suspected portion according to the information on the Raman scattered light detected by the Raman scattered light detection optical system 10B.

[0034] <Preventing misdiagnosis> In caries detection, it is difficult to completely stop the continuous movement of a subject such as a patient or a user such as a dentist. Therefore, the position where Raman spectroscopy measurement is performed may not coincide with the caries suspected area in the screening image. To prevent misdiagnosis due to such a mismatch, in this embodiment, screening may be performed after detection of Raman scattered light. For example, in this embodiment, as indicated by the dashed arrow in FIG. 3, Raman spectrum acquisition (step S305) may be performed a certain number of times, and then the process may return to acquiring the screening image in step S302. Then, image analysis in step S303 may be performed as needed, and the result may be used as information for determining whether or not the position of the Raman spectroscopy measurement needs to be corrected. Alternatively, the transition to step S302 may occur after a certain time has elapsed since the Raman spectrum acquisition.

[0035] The control unit 16 performs control as necessary to prevent misdiagnosis during caries detection (diagnosis). When a user such as a dentist diagnoses caries, the display control unit 164 displays, on the display device 15, an image of a specific caries suspected portion based on information about the transmitted light detected by the screening optical system 10A and an image of the specific caries suspected portion based on information about the Raman scattered light detected by the Raman scattered light detection optical system 10B. The control unit 16 acquires the "image of the specific caries suspected portion based on information about the transmitted light detected by the screening optical system 10A" by capturing a new image after acquiring an image of the Raman scattered light of the specific caries suspected portion by the Raman scattered light detection optical system 10B.

[0036] The control unit 16 displays such images on the display device 15, for example, in response to an input signal from the user, or automatically in conjunction with the caries diagnosis in step S307. The display control unit 164 displays the two images on the display device 15 side by side on one screen, or displays them superimposed as images of the same scale. This process makes it possible to refer to the measurement position in the Raman spectroscopy after measuring the caries suspected area, and to confirm the focusing position of the test light on the tooth T based on the screening image captured after the Raman spectroscopy measurement. This allows the user to easily notice an error in the measurement position even if a position different from the expected position is measured, preventing an erroneous diagnosis due to an error in the measurement position.

[0037] <Suppression of measurement fluctuations> As described above, it is difficult to completely stop the movement of the subject or the user during caries detection, so the control unit 16 may further perform control to suppress measurement fluctuations during detection of transmitted light or Raman scattered light during screening.

[0038] For example, the second test light irradiation position correction unit 165 corrects a deviation in the irradiation position of near-infrared light at the caries suspected portion according to information about the caries suspected portion. Correction of the deviation in the irradiation position can be realized, for example, by the caries detection device 1 transmitting a first signal indicating that the irradiation position remains the same as the original irradiation position, and transmitting a second signal indicating that the irradiation position has deviated from the original position.

[0039] Both the first signal and the second signal may be a visible signal such as an image displayed on the display device 15, or may be a signal in a form not displayed on a screen, such as an audio signal. The second signal may change depending on the magnitude of deviation from the initial position. This control is advantageous in that the position at which near-infrared light is focused is corrected appropriately and as needed during Raman spectroscopy measurement, keeping the near-infrared light focused position constant. This reduces the influence of the user's movements (e.g., hand tremors) on the measurement results.

[0040] Furthermore, for example, the vibration correction unit 166 cancels the influence of vibration of the screening optical system and the Raman scattered light detection optical system relative to the teeth. Such control is realized, for example, by detecting vibration due to hand shake of the inspection jig described above and moving the optical path of the near-infrared light in a direction that cancels out the vibration in response to the vibration. This control can be implemented in the same way as the vibration prevention function in optical devices such as cameras or telescopes. This control is also effective from the viewpoint of suppressing the influence of the movement of the user performing the measurement (e.g., hand tremors) on the measurement results.

[0041] Furthermore, for example, the difference detection unit 167 detects the positional difference between an image of a specific caries suspected region based on information on transmitted light detected by the screening optical system 10A and an image of the specific caries suspected region based on information on Raman scattered light detected by the Raman scattered light detection optical system 10B. This positional difference can be achieved using known techniques such as frame-to-frame subtraction and background subtraction. More specifically, by combining the difference images before and after movement with a position determination technique such as triangulation, it is possible to determine the distance moved (i.e., the positional difference). This control allows the user to confirm the positional deviation and, based on the direction and timing of the positional deviation, recognize the cause of the positional deviation and pay closer attention to the behavior that caused the deviation. This control is also effective in eliminating the influence of the user's movements (e.g., hand tremors) performing the measurement.

[0042] [Major effects of this embodiment] As human lifespans continue to increase worldwide, extending healthy lifespan, the period of time one can live without needing nursing care, has become an important social issue. Research and surveys to date have shown that elderly people with more teeth tend to have longer healthy lifespans. Periodontal diseases such as "dental caries" and "periodontal disease" account for a large proportion of tooth loss. Therefore, it is important to find ways to prevent or detect periodontal disease early.

[0043] Focusing on dental caries, a type of periodontal disease, detection of dental caries has traditionally been done using X-rays or by palpation by dentists. However, X-rays, which are the only widely used testing device, have difficulty detecting early-stage dental caries, and by the time they are detected, the caries has often already reached a stage where it must be removed.

[0044] Furthermore, palpation by dentists relies heavily on their own experience, making misdiagnosis an unavoidable problem. In recent years, it has become clear that early-stage caries can be treated without grinding the teeth, and the concept of preventive dentistry to prevent caries from progressing has gained momentum. As such, technology that can accurately detect early-stage caries has attracted attention and is desired in recent years.

[0045] Raman spectroscopy is capable of detecting caries in teeth with high accuracy, making it advantageous for detecting caries in the early stages. However, the Raman scattered light emitted by irradiating the tooth with inspection light is weak, which makes the Raman spectroscopy measurement time long. Normal teeth have a much larger surface area than caries, so from the perspective of appropriate measurement time, Raman spectroscopy is unsuitable for detecting caries across the entire tooth, a spatial range that is larger than that of caries.

[0046] In this embodiment, caries-suspected areas of the tooth T are detected using near-infrared transmitted light image information of the tooth T, and caries in the tooth T are detected by detecting near-infrared Raman scattered light for each of the caries detection areas. In this way, in this embodiment, by combining a near-infrared screening technique that can measure a wide area with Raman spectroscopy, it is possible to selectively measure only areas suspected of having caries using Raman spectroscopy. This shortens the measurement time compared to when caries is detected using Raman spectroscopy alone. Therefore, in this embodiment, it is possible to detect early caries quickly and accurately.

[0047] Furthermore, in this embodiment, the inspection light is near-infrared in both the screening optical system 10A and the Raman scattered light detection optical system 10B. Therefore, since the light emitted from the light source 11 is only near-infrared, it is possible to simplify the configuration of the light source 11. Furthermore, since there is only one inspection light, the Raman scattered light to be detected only needs to be separable from the single inspection light (near-infrared), which is advantageous from the viewpoint of simplifying the configuration of the Raman scattered light detection optical system 10B.

[0048] Furthermore, in this embodiment, the screening optical system 10A further includes a variable focal length lens 142, such as a liquid lens, as a variable focal length optical system. This makes it possible to easily change the irradiation range of the inspection light from the entire tooth T to the caries suspected portion. This is advantageous from the viewpoint of performing the screening of caries suspected portions and the caries detection using the same device.

[0049] Furthermore, in this embodiment, the Raman scattered light detection optical system 10B further includes an optical filter 141. The optical filter 141 can transmit only light of a specific wavelength, such as a component of the Raman scattered light generated from a caries suspected region, and can therefore detect only effective wavelengths, or detect light components of specific different wavelengths and easily determine their intensity ratios. This can further shorten the time required for caries detection.

[0050] Moreover, in this embodiment, the caries detection device 1 further includes a display device 15. Therefore, in caries detection by Raman spectroscopy, it is advantageous from the viewpoint of utilizing an image of transmitted light of the tooth T in screening.

[0051] In addition, when diagnosing dental caries using Raman spectroscopy, it is necessary to fix the suspected caries area and focus the light, but in reality, it is difficult to completely fix the patient's movement or the dentist's hand movement. Therefore, there is a high possibility that a non-carious area may be mistaken for a carious area and measured, resulting in an erroneous diagnosis. In this embodiment, various systems for correcting the measurement position can be introduced, making it possible to further reduce the possibility of such an erroneous diagnosis.

[0052] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0053] [Device configuration] FIG. 8 is a diagram schematically illustrating the configuration of a caries detection device according to this embodiment. As shown in FIG. 8, the caries detection device 2 includes a screening optical system 20A and a Raman scattered light detection optical system 20B. The screening optical system 20A is composed of a light source 21, a fluorescence light-receiving sensor 22, and an optical system 24. The screening optical system 20A is an optical system that irradiates the tooth T with excitation light, which is a first test light, from the light source 21 and detects fluorescence emitted from the tooth T. The Raman scattered light detection optical system 20B is composed of the light source 21, a Raman scattered light-receiving sensor 13, and the optical system 24. The Raman scattered light detection optical system 20B is an optical system that irradiates a caries suspected portion of the tooth T, which is detected from the above-described fluorescence information, with near-infrared light, which is a second test light, from the light source 21, and detects Raman scattered light emitted from the caries suspected portion.

[0054] In this embodiment, the fluorescence refers to fluorescence emitted from a tooth T irradiated with excitation light, which is the first test light. The excitation light may be any light that induces excitation specific to caries in a tooth with caries and generates fluorescence specific to caries. Visible light with a wavelength in the range of 300 to 800 nm may be used as the excitation light.

[0055] The light source 21 is a device that generates excitation light and near-infrared light. The excitation light is test light for screening, and is light that causes fluorescence to occur from teeth with caries. The excitation light has a shorter wavelength than the fluorescence, and is, for example, visible light that includes a portion of wavelengths selected from the wavelength range of 300 to 800 nm. The near-infrared light is test light for detecting Raman scattered light, and is light that causes Raman scattered light to occur from suspected caries areas. A high-output light source such as a semiconductor laser or a fiber laser is used as the light source 21. The light source 21 may be a wavelength-variable light source, or may be a plurality of light sources corresponding to the excitation light and the near-infrared light, respectively.

[0056] The fluorescence light-receiving sensor 22 is a sensor for detecting fluorescence generated when excitation light, which is the first inspection light, is irradiated onto the tooth T. An image sensor such as a CMOS camera or a CCD camera can be used as the fluorescence light-receiving sensor 22. In this embodiment, for example, a CMOS camera is used.

[0057] The optical system 24 is made up of optical filters 241 and 243 and a variable focal length lens 242 .

[0058] The optical filter 241 is disposed between the light source 21 and the tooth T, and reflects the excitation light from the light source 21 toward the tooth T and transmits other light. The optical filter 241 may be a bandpass filter, an edge filter, a longpass filter, a dichroic mirror, a notch filter, or the like. In this embodiment, the optical filter 241 is, for example, a notch filter, an edge filter, a dichroic mirror, or a longpass filter.

[0059] The variable focal length lens 242 is disposed between the optical filter 241 and the tooth T, and is disposed on the optical path of the inspection light from the optical filter 241 and the fluorescence or Raman scattered light from the tooth T. The variable focal length lens 242 is capable of focusing at least the inspection light from the optical filter 241 on the surface of the tooth T. In this embodiment, the variable focal length lens 242 is an optical configuration with a variable focal length, similar to the variable focal length lens 142, and is, for example, a liquid lens.

[0060] The optical filter 243 is disposed on the opposite side of the optical filter 241 from the variable focal length lens 242, and between the optical filter 241 and the fluorescence light receiving sensor 22 and the Raman scattered light receiving sensor 13. The optical filter 243 reflects fluorescence from the tooth T toward the fluorescence light receiving sensor 22 and transmits other light. In this embodiment, the optical filter 243 is, for example, an edge filter, a dichroic mirror, or a long-pass filter.

[0061] The functional configuration of this embodiment is substantially the same as that shown in FIG. 2, except that a fluorescent light receiving sensor 22 is connected to the control unit 16 instead of the transmitted light receiving sensor 12.

[0062] [Detection of dental caries] Caries detection using the caries detection device 2 can be carried out in substantially the same manner as in the first embodiment described above, except for screening.

[0063] <Screening> The control unit 16 causes the light source 21 to generate excitation light. The excitation light generated by the light source 21 is reflected by an optical filter 241, passes through a variable focal length lens 242 (liquid lens), and is then irradiated onto the tooth T. FIG. 9 is a diagram illustrating screening of caries suspected regions in this embodiment. The excitation light is reflected or scattered by a normal tooth T. On the other hand, for a tooth T with caries, the excitation light is absorbed by the caries region, as shown in FIG. 9, and generates fluorescence with a longer wavelength. For example, when the excitation light is irradiated onto the tooth T with caries, red fluorescence is generated, as shown in frame A2 in FIG. 10. FIG. 10 is a photograph showing an example of an image showing caries suspected regions obtained by screening in this embodiment. The photograph shown in FIG. 10 is cited from Tokuji Hasegawa, Dental Medicine Research, 33, 259-264 (2013).

[0064] The fluorescence passes through the variable focal length lens 242, passes through the optical filter 241, is reflected by the optical filter 243 toward the fluorescence light-receiving sensor 22, and is received and detected by the fluorescence light-receiving sensor 22. In this embodiment, the caries suspected part identifying unit 161 determines the presence or absence of such fluorescence based on, for example, a predetermined threshold value, and identifies the caries suspected part according to the information of the fluorescence detected by the screening optical system 20A.

[0065] <Other> In this embodiment, caries detection by Raman spectroscopy is performed in the same manner as in the first embodiment, except that the test light generated by the light source 21 is switched from excitation light to near-infrared light. In addition, in this embodiment, control for preventing misdiagnosis and suppressing measurement fluctuations can be performed in the same manner as in the first embodiment.

[0066] [Major effects of this embodiment] In this embodiment, caries suspected areas of the tooth T are detected based on fluorescent image information of the tooth T obtained by irradiating it with excitation light, and caries in the tooth T are detected by detecting near-infrared Raman scattered light for each of the caries detection areas. In this embodiment, the tooth T is screened based on the fluorescence specific to caries in the tooth T, and thus, similar to the first embodiment described above, it is possible to detect early caries quickly and accurately.

[0067] Furthermore, in this embodiment, the test light used in screening is light that causes caries-specific fluorescence to be generated from a caries-containing tooth, for example, light with a shorter wavelength than fluorescence, and the test light used in detecting Raman scattered light is near-infrared light. In this embodiment, the fluorescence emitted in the opposite direction to the traveling direction of the test light can be collected and detected. Therefore, both the screening optical system 20A and the Raman scattered light detection optical system 20B are positioned on the front side of the subject's oral cavity relative to the tooth T. Therefore, the test light is irradiated onto the tooth T from the front side of the oral cavity, and the detection light is detected on the front side. This makes it easier to detect caries-suspected areas and caries in the oral cavity of a subject, such as a patient.

[0068] Other Embodiments The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0069] For example, in an embodiment of the present invention, the display device 15 may also serve as an input device for a user. For example, the display device 15 may further include a touch panel.

[0070] In addition, in embodiments of the present invention, the caries suspected portion and the caries portion may be determined by a user such as a dentist. When the caries suspected portion is determined by a user, the subsequent detection of Raman scattered light may be performed automatically based on the user's input of the determination result. Alternatively, the user may manually perform Raman scattered light analysis on the automatically determined caries suspected portion and make a final decision on the caries detection based on the result.

[0071] In addition, in an embodiment of the present invention, a program for causing the control unit 16 to realize the desired control may be supplied to the control unit 16 via any wired or wireless transmission medium. Also, some or all of the functions of each control block in the control unit 16 may be realized by a logic circuit. The control unit 16 may be, for example, an integrated circuit formed with a logic circuit that functions as each of the above control blocks. Also, the functions of each of the above control blocks may be realized by, for example, a quantum computer.

[0072] Furthermore, each process described in the embodiments of the present invention may be executed by AI (Artificial Intelligence). For example, in the embodiments of the present invention, the determination of caries candidate areas, determination of caries areas, or caries diagnosis may be executed by AI. The aforementioned Patent Document 3 proposes a calculation formula for quantitatively evaluating the degree of caries progression from the Raman spectrum of teeth. Based on the knowledge of such quantitative evaluation, it is expected that AI will provide sufficiently useful results regarding caries candidate areas, caries areas, and their diagnosis. In the embodiments of the present invention, the AI ​​may operate in a control unit or in another device (for example, an edge computer or a cloud server).

[0073] 〔summary〕 As is clear from the above description, the caries detection device (1, 2) in the embodiment of the present invention includes a screening optical system (10A, 20A) that irradiates a tooth (T) with a first test light from a light source (11, 21) and detects light transmitted through the tooth or fluorescence emitted from the tooth, and a Raman scattered light detection optical system (10B, 20B) that irradiates a caries suspected portion of the tooth identified from information on the transmitted light or fluorescence detected by the screening optical system with a second test light from the light source and detects Raman scattered light emitted from the caries suspected portion. Therefore, the caries detection device can detect caries by detecting Raman scattered light in a shorter time than when screening and caries detection are performed by Raman spectroscopy.

[0074] The caries detection device according to an embodiment of the present invention may further include a caries suspected portion identifying unit that identifies a caries suspected portion based on information on transmitted light or fluorescence detected by the screening optical system. This configuration is even more effective in terms of quickly determining a caries suspected portion and thus realizing caries detection in a short period of time.

[0075] Furthermore, the caries detection device according to the embodiment of the present invention may further include a caries detection unit that detects caries in a caries suspected portion in accordance with information on the Raman scattered light detected by the Raman scattered light detection optical system. This configuration is even more effective in terms of realizing caries detection in a short period of time.

[0076] In an embodiment of the present invention, both the first test light and the second test light may be near-infrared light. This configuration is even more effective from the viewpoint of simplifying the configuration of the caries detection device, since the light source only needs to be a device that generates a single light (near-infrared light).

[0077] Alternatively, in an embodiment of the present invention, the first test light may be light (excitation light) with a wavelength shorter than that of fluorescence, and the second test light may be near-infrared light. This configuration makes it possible to configure a caries detection device that can detect caries suspected areas and caries in the target tooth from the front side of the oral cavity, and is therefore even more effective in terms of facilitating the caries detection operation.

[0078] In an embodiment of the present invention, the screening optical system may further include a variable focal length optical system that can change the irradiation range of the first test light on the tooth. This configuration is more effective from the viewpoint of constructing a simple optical system that can detect both caries suspected regions and caries.

[0079] Furthermore, in an embodiment of the present invention, the variable focal length optical system may further include a liquid lens. This configuration is even more effective from the viewpoint of constructing a simple optical system capable of detecting both caries suspected regions and caries.

[0080] Furthermore, the caries detection device according to the embodiment of the present invention may further include a second test light irradiation position correction unit that corrects a deviation in the irradiation position of the second test light on the caries suspected portion in accordance with information on the caries suspected portion. This configuration makes it possible to correct the position where the test light is focused as needed during Raman spectroscopy measurement to keep the focusing position constant, and is therefore even more effective in suppressing the influence of movements (e.g., hand tremors) of the user, such as a dentist, performing the measurement on the detection results.

[0081] Furthermore, the caries detection device according to an embodiment of the present invention may further include a vibration correction unit that cancels the influence of vibration of the screening optical system and the Raman scattered light detection optical system on the teeth. This configuration is even more effective in suppressing the influence of the user's hand vibration on the detection results when detecting caries suspected areas and caries.

[0082] In an embodiment of the present invention, the Raman scattered light detection optical system may further include a filter that transmits only light of a specific wavelength from the Raman scattered light generated from the caries suspected region. This configuration makes it possible to detect a light component of a specific wavelength or the intensity ratio of light components of different wavelengths, and is even more effective from the viewpoint of realizing caries detection in a short period of time.

[0083] Furthermore, the caries detection device in an embodiment of the present invention may further include a display device (15) that displays one or both of an image based on information about transmitted light or fluorescence detected by the screening optical system and an image based on information about Raman scattered light detected by the Raman scattered light detection optical system. This configuration enables caries detection using images acquired during caries detection of caries suspected areas and caries, and is even more effective from the perspective of improving the accuracy of caries detection.

[0084] Furthermore, the caries detection device in an embodiment of the present invention may further include a display control unit that displays, on a display device, an image of a specific caries suspected portion based on information on transmitted light or fluorescence detected by the screening optical system, and an image of a specific caries suspected portion based on information on Raman scattered light detected by the Raman scattered light detection optical system. This configuration makes it possible to easily confirm each detected portion using images acquired during caries detection, and is even more effective from the perspective of preventing erroneous caries detection.

[0085] Furthermore, the caries detection device according to an embodiment of the present invention may further include a difference detection unit that detects the difference in position between an image of a specific caries suspected portion based on information about transmitted light or fluorescence detected by the screening optical system and an image of the specific caries suspected portion based on information about Raman scattered light detected by the Raman scattered light detection optical system. This configuration makes it possible to easily confirm, after caries detection, whether the detected position of the caries suspected portion and the detected position of the caries suspected portion based on the caries suspected portion are correct. This is therefore even more effective in preventing erroneous caries detection.

[0086] The above-described configuration of the embodiment of the present invention enables accurate, rapid, and easy detection of periodontal diseases such as dental caries from the early stages. Therefore, the embodiment of the present invention is expected to lead to an extension of healthy life expectancy through early detection of periodontal diseases, and to contribute to ensuring healthy lives for people as part of the Sustainable Development Goals (SDGs). [Explanation of symbols]

[0087] 1, 2 Caries detection device 10A, 20A screening optical system 10B, 20B Raman scattering light detection optical system 11, 21 Light source 12 Transmitted light receiving sensor 13 Raman scattering light receiving sensor 14, 24 Optical system 15 Display device 16 Control Unit 22 Fluorescence sensor 141, 241, 243 Optical filters 142, 242 variable focal length lens 161 Caries candidate area identification department 162 Caries detection unit 163 Focal length control unit 164 Display control unit 165 Second inspection light irradiation position correction unit 166 Shake compensation unit 167 Difference detection unit

Claims

1. a screening optical system that irradiates a first test light from a light source onto the teeth and detects light transmitted through the teeth or fluorescence emitted from the teeth; a Raman scattered light detection optical system that irradiates a caries suspected portion of the tooth identified from information on the transmitted light or the fluorescence detected by the screening optical system with second test light from the light source and detects Raman scattered light generated from the caries suspected portion; A caries detection device having:

2. The caries detection device according to claim 1 , further comprising a caries suspected portion identifying unit that identifies the caries suspected portion according to information on the transmitted light or the fluorescent light detected by the screening optical system.

3. The caries detection device according to claim 1 or 2, further comprising a caries detection unit that detects caries in the caries suspected portion based on information about the Raman scattered light detected by the Raman scattered light detection optical system.

4. The caries detection device according to any one of claims 1 to 3, wherein the first test light and the second test light are both near-infrared light.

5. 4. The caries detection device according to claim 1, wherein the first test light has a wavelength shorter than that of the fluorescence, and the second test light is near-infrared light.

6. A caries detection device according to any one of claims 1 to 5, wherein the screening optical system further includes a variable focal length optical system capable of changing the irradiation range of the first inspection light on the tooth.

7. The caries detection device of claim 6 , wherein the variable focal length optical system further comprises a liquid lens.

8. A caries detection device described in any one of claims 1 to 7, further comprising a second test light irradiation position correction unit that emits a signal indicating that the irradiation position of the second test light at the caries suspected area has deviated from its original position.

9. The caries detection device according to any one of claims 1 to 8, further comprising a vibration correction unit that cancels out the influence of vibration of the screening optical system and the Raman scattered light detection optical system relative to the tooth.

10. A caries detection device according to any one of claims 1 to 9, wherein the Raman scattered light detection optical system further includes a filter that transmits only light of a specific wavelength from the Raman scattered light generated from the caries suspected area.

11. A caries detection device as described in any one of claims 1 to 10, further comprising a display device that displays one or both of an image based on information about the transmitted light or the fluorescence detected by the screening optical system and an image based on information about the Raman scattered light detected by the Raman scattered light detection optical system.

12. The caries detection device described in claim 11, further comprising a display control unit that displays on the display device an image of a specific caries suspected area based on information on the transmitted light or the fluorescence detected by the screening optical system, and an image of the specific caries suspected area based on information on the Raman scattered light detected by the Raman scattered light detection optical system.

13. The caries detection device described in claim 12, further comprising a difference detection unit that detects the difference in position between an image of a specific caries suspected area based on information about the transmitted light or the fluorescence detected by the screening optical system and an image of the specific caries suspected area based on information about the Raman scattered light detected by the Raman scattered light detection optical system.

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