JP2009090091A - Dental observation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To observe a caries located at a position that cannot be directly viewed, such as one of the adjacent surfaces between teeth, with high contrast, and its spread and degree of invasion. <P>SOLUTION: A dental observation apparatus 1 includes: an irradiating unit 2 radiating illumination light including an infrared region; a detecting unit 3 separately detecting fluorescence generated from a caries portion B by irradiation with the illumination light and scattered light of the illumination light at the tooth; and an image processing unit 4 which forms a fluorescence image from the fluorescence detected by the detecting unit 3, which forms a scattered light image capable of identifying a boundary between an enamel layer and a dentine layer, the layers having different scattering properties, from the intensity of the scattered light detected by the detecting unit 3, and which combines the fluorescence image and the scattered light image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dental observation apparatus.

  Conventionally, dental caries are generally confirmed by visual inspection or X-ray inspection by a dentist. In the visual inspection, there is an inconvenience that it is difficult to confirm a caries in a place where it cannot be directly viewed, such as a minute caries and an adjacent surface of a tooth at an early stage. In addition, since X-ray inspection involves X-ray exposure, there is a disadvantage that it cannot be performed frequently.

  In order to avoid these inconveniences, early detection of dental caries and observation of caries at sites that are difficult to observe, there is a technology for imaging the light transmitted through the inside of the tooth by irradiating white light from the outside of the tooth. It is known (for example, refer to Patent Document 1).

US Pat. No. 6,201,880

  However, in the technique of Patent Document 1, since the white light that is easily affected by scattering inside the tooth is used, there is a disadvantage that the caries generated in the portion that cannot be directly viewed from the tooth surface cannot be observed with high contrast. is there.

  The present invention has been made in view of the above-described circumstances, and is capable of observing caries in a place that cannot be directly viewed, such as the adjacent surface of a tooth, with high contrast and observing its spread and depth of penetration. The object is to provide an observation device.

In order to achieve the above object, the present invention provides the following means.
The present invention provides an irradiation unit that irradiates illumination light including an infrared region, a detection unit that separately detects fluorescence generated from a caries portion of a tooth by irradiation of the illumination light and scattered light in the tooth of the illumination light And a fluorescence image can be generated based on the fluorescence detected by the detection unit, and the boundary between the enamel layer and the dentin layer having different scattering characteristics can be identified based on the intensity of the scattered light detected by the detection unit. A dental observation apparatus including an image processing unit that generates a scattered light image and synthesizes the fluorescence image and the scattered light image is provided.

  According to the present invention, when the illumination light including the infrared region is irradiated from the irradiation part to the tooth, fluorescence is emitted from the caries part existing in the tooth, while the scattered light of the illumination light is generated from the entire tooth. By detecting these separately by the detection unit and synthesizing the fluorescence image and the scattered light image, it is possible to generate a composite image including the entire tooth and the caries portion disposed on a part thereof with high contrast. .

  Fluorescence and scattered light can be detected in a time-divided manner or in a distinguishable manner by detecting with different wavelengths depending on the selection of the fluorescent dye. Therefore, it is possible to clearly detect a caries portion in a place where it cannot be directly viewed, such as an adjacent surface of a tooth.

  In this case, since the enamel layer and the dentin layer in the tooth have different scattering characteristics, the scattered light from the enamel layer and the scattered light from the dentin layer have different intensities. Therefore, the image processing unit can obtain a scattered light image that can identify the boundary between the enamel layer and the dentin layer based on the difference in intensity of the scattered light. As a result, by confirming the position of the caries portion with respect to the boundary, it is possible to easily observe the spread and depth of the caries portion.

In the above invention, the image processing unit compares the intensity of the scattered light acquired by the detection unit with a predetermined threshold value, and generates a scattered light image capable of identifying the boundary between the enamel layer and the dentin layer. It is good to do.
As described above, since the enamel layer and the dentin layer in the tooth have different scattering characteristics, the scattered light from the enamel layer and the scattered light from the dentin layer have different intensities. Therefore, by setting an appropriate threshold value, it is possible to distinguish these scattered lights, and it is possible to easily generate a scattered light image that can identify the boundary between them.

  Moreover, in the said invention, the said irradiation part further irradiates visible light, the said detection part further detects the scattered light of visible light, and the said image process part is the visible light detected by the said detection part. A visible scattered light image may be generated based on the intensity, and a scattered light image capable of identifying the boundary between the enamel layer and the dentin layer may be generated by comparison with the visible scattered light image.

  By doing in this way, the visible light irradiated from the irradiation unit is detected by the detection unit, and the visible scattered light image generated based on the detected visible light intensity by the image processing unit and the illumination in the infrared region The scattered light image obtained by irradiating light is compared. Thereby, the distinction between the scattered light from the enamel layer of the tooth and the scattered light from the dentin layer can be clarified. Examples of the comparison include performing a difference calculation or division between images.

Moreover, in the said invention, the said image process part is good also as giving a different color to the area | region corresponding to the caries part of the said fluorescence image, and the enamel layer and dentin layer of the said scattered light image, and synthesize | combining them.
In this way, the caries part, the enamel layer and the dentin layer can be displayed clearly distinguishably, and the extent and depth of penetration of the caries part relative to the boundary between the enamel layer and the dentin layer can be determined. It becomes possible to observe more easily.

Moreover, in the said invention, the depth determination which determines the depth of penetration of the said caries part by comparing the distance from the surface of the said enamel layer to the said boundary, and the distance from the said caries part to the said boundary It is good also as providing a part.
In this way, when the distance from the caries part to the boundary is shorter than a predetermined ratio with respect to the distance from the surface of the enamel layer to the boundary with the dentin layer, the depth determination part is It can be determined that the depth of the part is high. Thereby, in the treatment of a tooth, the treatment method can be easily selected.

  Moreover, in the said invention, the said irradiation part irradiates 2nd illumination light from the 1st irradiation part which irradiates 1st illumination light from the side surface side of the said tooth, and the occlusal surface side of the said tooth. The detection unit may be arranged to face the first irradiation unit with the tooth interposed therebetween.

  By doing in this way, by detecting the transmitted light in the tooth of the 1st illumination light irradiated from the side surface side of a tooth by a detection part, an enamel layer and an ivory based on the difference in the intensity of the scattered light in a tooth It is possible to acquire a scattered light image that can identify the boundary with the quality layer. Further, the second illumination light irradiated from the occlusal surface side of the tooth excites the fluorescent material corrected in the caries portion existing in the tooth to emit fluorescence. In this case, since the fluorescence generated when the second illumination light is incident from the occlusal surface side is detected by the detection unit facing the side surface side, the incident second illumination light is detected by the detection unit. It is difficult to obtain a fluorescent image with high contrast. Therefore, it is possible to clearly detect a caries portion in a place where it cannot be directly viewed, such as an adjacent surface of a tooth.

Moreover, in the said invention, it arrange | positions between the said 1st polarizing member arrange | positioned between the said 1st irradiation part and the said tooth, the said tooth, and the said detection part, The said 1st polarizing member, May include a second polarizing member having a different polarization direction.
The first illumination light transmitted through the gap between the teeth by the first and second polarizing members, the direct reflected light of the first illumination light on the teeth, etc. are prevented from entering the detection unit, and the contrast is high. A scattered light image can be acquired.

Moreover, in the said invention, it is preferable that said 2nd illumination light is near infrared light.
By using near-infrared light, autofluorescence can be suppressed and a fluorescence image with high contrast due to drug fluorescence can be acquired.

Moreover, in the said invention, it is arrange | positioned between the said tooth and the said detection part, You may provide the interruption | blocking means which permeate | transmits 1st illumination light and interrupts | blocks 2nd illumination light.
By doing in this way, when irradiating the 1st illumination light, the 1st illumination light scattered in the tooth permeate | transmits the interruption | blocking means, is detected by the detection part, and a scattered light image can be obtained. On the other hand, when irradiating the second illumination light, the second illumination light reflected on the teeth is blocked by the blocking means and is prohibited from entering the detection unit. Thereby, a fluorescence image with high contrast can be acquired.

In the above-mentioned invention, the illumination light switching means for switching the first illumination light and the second illumination light in a time-sharing manner is provided, and the detection unit is configured to switch the illumination light by the illumination light switching means. The fluorescence or the scattered light may be detected in synchronization.
In this way, when the first illumination light and the second illumination light switched in time division by the illumination light switching means are respectively irradiated, the detection unit detects fluorescence or scattered light, so that A fluorescence image and a scattered light image can be acquired without affecting each other by one detection unit.

Moreover, in the said invention, the semiconductor light source provided with the insertion part which can be inserted in an oral cavity, and the said irradiation part arrange | positioned at the front-end | tip part of the said insertion part may be sufficient.
By doing in this way, a dental observation apparatus can be comprised compactly.

  Moreover, in the said invention, the said 1st illumination light and the 2nd illumination light are near-infrared light, The illumination light switching means which switches the said 1st illumination light and the said 2nd illumination light by a time division | segmentation And a blocking unit that blocks the incident of the second illumination light on the detection unit when switched to the second illumination light by the illumination light switching unit, and the detection unit includes the illumination unit The fluorescence or the scattered light may be detected in synchronization with the switching timing of the illumination light by the light switching means.

  In this way, even if near-infrared light having an equivalent wavelength band is used as the first and second illumination lights, the fluorescence image and the scattered light are not affected by a single detection unit. Images can be acquired. As the blocking means, a filter inserted into and removed from the optical path or a switchable liquid crystal filter can be employed.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the caries in the place which cannot look directly like the adjacent surface of a tooth can be observed with high contrast, and the breadth and depth of penetration can be observed.

A dental observation apparatus 1 according to a first embodiment of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the dental observation apparatus 1 according to the present embodiment irradiates a tooth A with illumination light including an infrared region, and irradiation of illumination light from the irradiation unit 2. Is generated by the detection unit 3 that detects the light generated from the caries portion B of the tooth A, the image processing unit 4 that generates an image based on the intensity of the light detected by the detection unit 3, and the image processing unit 4 And a display unit 5 for displaying the displayed image.

  As shown in FIG. 2, the irradiating unit 2 includes a light source 6 that generates light having a broadband wavelength, and light emitted from the light source 6. 800 nm and 820 to 870 nm), a rotary filter 7 having two types of filters 7a and 7b for selecting illumination light, a condensing lens 8 for condensing the illumination light selected by the rotary filter 7, and the condensing An optical fiber 9 that guides the illumination light collected by the lens 8 and irradiates the tooth A from the emission end is provided.

The light source 6 may be, for example, an LED, an SLD, a halogen lamp, a xenon lamp, or a laser light source.
The detection unit 3 is disposed on the opposite side of the irradiation unit 2 with the tooth A interposed therebetween, and the light reception filter 10 that blocks light in a predetermined wavelength band (for example, 820 nm or less) incident from the tooth A, and the light reception filter And a light detector 11 that detects light transmitted through the light source 10. The photodetector 11 is an image sensor such as a CCD or a CMOS, for example.

  The image processing unit 4 is a fluorescent image based on the intensity of the fluorescence detected by the detection unit 3 when the illumination light of the first wavelength band (750 to 800 nm) is irradiated from the irradiation unit 2 to the tooth A. And the scattered light image based on the intensity of the scattered light detected by the detection unit 3 when the illumination light of the second wavelength band (820 to 870 nm) is irradiated to the tooth A from the irradiation unit 2 Is supposed to generate. That is, the fluorescence image and the scattered light image are generated in synchronization with the rotation of the rotary filter 7.

The image processing unit 4 generates a scattered light image obtained by binarizing the generated scattered light image based on a predetermined threshold value.
Furthermore, the image processing unit 4 synthesizes the generated fluorescence image and the scattered light image and outputs them to the display unit 5.

The operation of the dental observation apparatus 1 according to this embodiment configured as described above will be described below.
In order to observe the tooth A using the dental observation apparatus 1 according to this embodiment, an appropriate fluorescent agent (for example, ICG) is administered to the tooth A, and then the emission end 9a of the optical fiber 9 is connected. The detection unit 3 is arranged opposite to the tooth A, the opposite side of the optical fiber 9 with the tooth A interposed therebetween, and light is emitted from the light source 6.

  Then, by rotating the rotary filter 7, when one filter 7 a is disposed on the optical path, the illumination light in the first wavelength band (750 to 800 nm) is collected by the condenser lens 8, and the optical fiber 9 is guided to the surface of the tooth A. When illumination light in this wavelength band is irradiated, the fluorescent agent accumulated in the caries portion B is excited to generate fluorescence.

The generated fluorescence is emitted in all directions, passes through the light receiving filter 10 disposed opposite to the tooth A, and is detected by the photodetector 11. 2-dimensional intensity signal of the fluorescence detected by the optical detector 11, by being sent to the image processing unit 4 is generated as the fluorescence image G _1. Since the light receiving filter 10 is set so as to block the illumination light in the first wavelength band, only the fluorescence of the illumination light itself is detected by the photodetector 11 without passing through the light receiving filter 10. That is, at this time, as shown in FIG. 3, the fluorescence image G ₁ having a luminance only caries portion B is generated.

  On the other hand, when the other filter 7b of the rotary filter 7 is disposed on the optical path, the illumination light in the second wavelength band (820 to 870 nm) is collected by the condenser lens 8 and guided by the optical fiber 9. Then, the surface of the tooth A is irradiated. Unlike the illumination light in the first wavelength band, the illumination light in the second wavelength band does not excite the fluorescent agent and thus does not generate fluorescence. However, the illumination light is scattered at each part inside the tooth A, and is emitted to the outside of the tooth A as scattered light.

Since the emitted scattered light has a wavelength band that can be transmitted through the light receiving filter 10 disposed to face the tooth A, the scattered light passes through the light receiving filter 10 and is detected by the photodetector 11.
In this case, the tooth A is generally composed of a surface enamel layer A ₁ and an inner dentin layer A _2. The scattering characteristics of the enamel layer A _{1 and} the scattering characteristics of the dentin layer A ₂ are shown in FIG. As shown in FIG. This difference in scattering characteristics is particularly noticeable in the infrared region.

Thus, the scattered light received by the detecting unit 3 through the enamel layer A _1, a and a light receiving scattered light by the detection unit 3 is transmitted through the dentine layer A ₂ different from its strength, in FIG. 5 As shown, a scattered light image G ₂ is acquired in which the dentin layer A ₂ is dark and the enamel layer A ₁ is bright.
In the image processing unit 4, by binarizing the obtained scattered light image G ₂ in a predetermined threshold value, as shown in FIG. 6, the boundary A ₃ between the enamel layer A ₁ and the dentine layer A ₂ it is possible to generate a scattered light image G ₃ with clear.

Further, the image processing unit 4 combines the fluorescent image G ₁ and the scattered light image G ₃ generated as described above, and as shown in FIG. 7, the enamel layer A ₁ and the dentin layer A ₂ , a composite image G ₄ that clearly shows the caries portion B can be generated in the entire image of the tooth A with the boundary A 3 clearly defined.

As described above, according to the dental observation device 1 according to the present embodiment, the illumination light in the infrared region that is difficult to scatter is used to accumulate in the caries portion B in the place where the tooth A cannot be seen directly like the adjacent surface. fluorescent agents also exciting, the fluorescence image and the fluorescence image G ₁ having a high contrast, by using a difference in scattering properties clearly the boundary a ₃ between the enamel layer a ₁ and the dentine layer a ₂ since combining the overall scattered light image G ₃ of the tooth a that there is the advantage that it is possible to observe the extent and depth of invasion of the caries portion B of the tooth a clearer.

  In the present embodiment, the wavelength band of the illumination light to be irradiated is exemplified, but the present invention is not limited to this, and any illumination light including an infrared region can be used. In addition, a fluorescent agent can be selected as appropriate. For example, illumination light having both a visible light region and an infrared region can be used instead of light in the infrared region only. Here, the light in the visible light region is used to excite the fluorescent agent accumulated in the caries portion B to generate fluorescence. On the other hand, the light in the infrared region is scattered at each part inside the tooth A and detected by the photodetector 11 as scattered light. In this case, as the fluorescent agent, an agent that is excited by light in the visible light region to generate fluorescence may be used. Further, the rotary filter 7 may be provided with two types of filters for selecting illumination light in the visible light region and illumination light in the infrared region.

Moreover, in this embodiment, although the system which detects the scattered light which permeate | transmitted the tooth A by employ | adopting the irradiation part 2 and the detection part 3 on both sides of the tooth A was employ | adopted, it replaces with this and FIG. As shown, a method of detecting scattered light reflected on the same side as the side irradiated with illumination light on the tooth A may be employed.
In this case, the scattered light image G ₂ acquired by the light detection unit 11, and that the luminance distribution is reversed to the above. Further, in FIG. 8, illumination light is irradiated from one side of the detection unit 3 facing the tooth A, but instead, illumination light may be irradiated from both sides of the detection unit 3.

In the present embodiment, the scattered light image G ₂ is binarized by a predetermined threshold value set in advance to clarify the boundary A ₃ between the enamel layer A ₁ and the dentin layer A _{2. 3} was decided to generate, but instead of this, by calculating the difference or ratio between the visible light of the scattered light image obtained by irradiation with visible light (not shown), and the enamel layer a ₁ it is also possible to clarify the boundaries a ₃ between the dentine layer a _2. In this case, in order to irradiate visible light, the rotary filter 7 may be provided with a third filter that transmits visible light.

Then, after matching the level of the acquired two scattered light images, by performing a difference operation between the images, the intensity distribution based on the difference in scattering properties of the enamel layer A ₁ and the dentine layer A ₂ and the difference is actualized, may further generate an overall image of the tooth a with clear precisely boundary a _3.
Further, different colors are given to the respective regions of the obtained fluorescent image G ₁ of the caries portion B, the scattered light image G ₃ of the enamel layer A ₁ and the dentin layer A ₂ , and these regions are displayed in different colors. It may be.

Although two types of illumination light are generated by the rotary filter 7, as shown in FIG. 9, two or more light sources 6 that generate illumination light of different wavelength bands are identical by the mirror 12 and the dichroic mirror 13. You may make it enter into an optical path.
Further, as shown in FIG. 10, the rotary filter 7 may be eliminated, and two types of illumination light may be generated by the wavelength tunable laser light source 6 ′.
Further, as shown in FIG. 11, a liquid crystal filter 14 or a comb filter may be employed instead of the rotary filter 7.

  In addition, as shown in FIG. 12, a fixed irradiation filter 15 may be disposed instead of the rotary filter 7, and a rotary filter 16 may be disposed instead of the light receiving filter 10. In this case, for example, as shown in FIG. 13, the irradiation filter 15 transmits light in the wavelength band of 750 to 800 nm, and the rotary filter 16 on the detection unit 3 side transmits light in the wavelength band of 800 nm or less. What is necessary is just to provide the filter 16a for scattered light observation, and the filter 16b for fluorescence observation which permeate | transmits the light of a wavelength band 820 nm or more.

Further, as shown in FIG. 14, rotary filters 7 and 16 that are rotated in synchronization may be disposed in each of the irradiation unit 2 and the detection unit 3.
In this case, for example, as shown in FIG. 15, the rotary filter 7 of the irradiation unit 2 includes a scattered light observation filter 7 a that transmits light in the wavelength band of 600 to 700 nm, and a wavelength band of 750 to 800 nm. What is necessary is just to provide the filter 7b for fluorescence observation which permeate | transmits light. Further, the rotary filter 16 of the detection unit 3 includes a scattered light observation filter 16a that transmits light in a wavelength band of 700 nm or less and a fluorescence observation filter 16b that transmits light in a wavelength band of 820 nm or more. You can do that.

Further, as shown in FIG. 16, two photodetectors 11 may be arranged in the detection unit 3 so as to form a convergence angle so that three-dimensional observation having a depth can be performed.
By doing in this way, it becomes possible to observe the breadth and depth of penetration of the caries part B three-dimensionally and to perform more accurate diagnosis.

In addition, as shown in FIG. 17, the pulse laser light source 6 ″ is used as the light source, and the pulse laser beam is condensed on the caries part B, whereby second and third harmonics are generated in the caries part B. In this way, fluorescence may be generated.
By doing so, as shown in FIG. 18, the illumination light having a wavelength sufficiently longer than the excitation wavelength of the fluorescent agent can be used, and the fluorescent agent is excited by the highly transmissive illumination light inside the tooth A. Therefore, there is an advantage that the caries portion B can be observed with high accuracy.

  Further, as shown in FIG. 19, a pulse laser light source 6 ″ is used as a light source, and a phase adjustment device 17 that switches between a first phase for detecting scattered light and a second phase for detecting fluorescence is used. In the figure, reference numeral 18 denotes a frequency oscillator, which makes it possible to easily separate and observe scattered light and fluorescence using the lifetime of fluorescence.

In each of the above embodiments, the image processing unit 4 may be provided with a depth determination unit (not shown).
As described above, in the image processing unit 4, since the boundary A ₃ between the enamel layer A ₁ and the dentine layer A ₂ is clearly extracted, as shown in FIG. 20, the size of the caries portion B Based on a and the thickness dimension b of the enamel layer A _{1 at} the site where the caries portion B is generated, the depth determination unit may determine the depth of the caries portion B. . In this way, when the a> b, it can be determined that the caries portion B has progressed to dentine layer A _2, the case of a <b, caries portion B is remains in the enamel layer A ₁ Can be determined. Therefore, there is an advantage that a more appropriate treatment method can be quickly selected based on the determination result.

Next, a dental observation apparatus 20 according to a second embodiment of the present invention will be described below with reference to FIGS.
In the description of the present embodiment, portions having the same configuration as those of the dental observation apparatus 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIGS. 21 and 22, the dental observation apparatus 20 according to this embodiment includes two light sources 21 and 22 that generate _first and _second illumination lights L ₁ and L ₂ in different wavelength bands, and The optical fibers (light guide members) 23 and 24 for guiding the illumination lights L ₁ and L ₂ from the light sources 21 and 22, and the tip surfaces 23 a and 24 a of the optical fibers 23 and 24 and the teeth A, respectively. The first polarizing plate 25 is disposed, and the second polarizing plate 26 is disposed between the light receiving filter 10 and the photodetector 11 and has a polarization plane different from that of the first polarizing plate 25. A control unit 27 is connected to the two light sources 21 and 22 and the image processing unit 4.

As shown in FIG. 23, the two light sources 21 and 22 are light having a wavelength band of 820 to 870 nm as the first illumination light L ₁ and L ₂ , and a wavelength band of 750 to 800 nm as the second illumination light L _2. Each of the near infrared lights is emitted.
The distal end surface 23a of the optical fiber 23 to the first light guide illumination light L ₁ of the are arranged in a direction opposite to the side surface of the adjacent surfaces near the two teeth A. Optical fiber 24 to the second light guiding illumination light L ₂ of is branched into two, two tip surfaces 24a, as shown in FIGS. 21 and 22, respectively occlusal surface of the tooth A two above It is arranged toward the opposite direction.

The first polarizing plate 25 and the second polarizing plate 26 have different polarization planes and are so-called crossed Nicols. Thereby, the direct light or the reflected light of the first illumination light L ₁ emitted from the distal end surface 23 a of the optical fiber 23 that guides the _first illumination light L ₁ toward the side surface of the tooth A is detected by the photodetector. 11 can be prevented from entering.
The light receiving filter 10 blocks light of 820 nm or less.

As shown in FIG. 24, the control unit 27 controls the two light sources 21 and 22 to emit the first and second illumination lights L ₁ and L ₂ alternately in a time-division manner, and the illumination light L _In synchronization with the switching timing between ₁ and L ₂ , the scattered light image is sent to the image processing unit 4 based on the intensity of the scattered light detected by the photodetector 11 when the first illumination light L ₁ is emitted. is generated, the second illumination light L ₂ of the is adapted to generate a fluorescent image to the image processing unit 4 based on the intensity of the fluorescence detected by the photodetector 11 as it is being injected.
When the transmitted light and the fluorescence are compared, the intensity of the transmitted light is sufficiently high. Therefore, in the example shown in FIG. 24, the irradiation time of the _second illumination light L ₂ is set in order to sufficiently secure the exposure time of the weak fluorescence. It is set to be longer than the first irradiation time of the illumination light L _1.

According to the dental observation apparatus 20 according to the thus constructed present embodiment, the first illumination light L ₁ to the intensity of the scattered light is irradiated from the side is detected by the photodetector 11 of the tooth A based on the scattered light image generated by the image processing unit 4, first the first direct light and reflected light of the illumination light L ₁ is arranged a cross-Nicol, due to being blocked by the second polarizer 25 Thus, a high-contrast scattered light image including a large amount of scattered light scattered inside the tooth A can be obtained.

The fluorescent image generated by the image processing unit 4 based on the intensity of the fluorescence detected by the photodetector 11 is irradiated from the occlusal surface side of the second illumination light L ₂ of the tooth A, the second lighting since the detection direction of the incident direction and the fluorescent light L ₂ are different, it is the second illumination light L ₂ is hardly detected by the photodetector 11, the light receiving filter 10 of the second illumination light L ₂ Since the incidence on the photodetector 11 is blocked, a fluorescent image with high contrast can be obtained.

FIG. 25 shows changes in the transmittance of the tooth A for each wavelength of light normalized by the luminance at a wavelength of 1000 nm.
Specifically, a part of the enamel region of the image of the tooth A is irradiated with light while changing the wavelength from 488 nm to 1000 nm, and the average value of the luminance of the irradiated region of interest is measured. . Then, this average value is normalized by the exposure time, the irradiation light amount, and the irradiation wavelength width, and the transparency at each wavelength is 10 × log (luminance / luminance at 1000 nm) on the basis of the normalized luminance average value at the wavelength of 1000 nm. Calculated.

FIG. 26 shows the change in autofluorescence for each excitation wavelength normalized by the brightness of autofluorescence at a wavelength of 790 nm detected at an excitation wavelength of 740 nm.
Specifically, the excitation light is irradiated to a part of the region of interest at the boundary between the enamel and the dentin in the image of the tooth A, and the average value of the brightness of the autofluorescence generated at that time is measured. Then, this average value is normalized by the exposure time, irradiation light amount, irradiation wavelength width, and detection wavelength width, and other autofluorescence intensities are 10 × log (autologous) based on the autofluorescence intensity at a wavelength of 790 nm when excited at a wavelength of 740 nm. (Fluorescence intensity / self-fluorescence intensity at 740 nm excitation, 790 nm detection).

According to these figures 25 and 26, although the first transparent in the wavelength band 820~870nm of the illumination light L ₁ is lower in this embodiment, since the autofluorescence hardly occurs, a high scattered light image contrast It can be seen that it can be acquired. Similarly, autofluorescence is small in the second wavelength band 750~800nm of the illumination light L _2, it is understood that it is possible to obtain a high fluorescence contrast image.

In addition, according to FIG. 27, when the tooth A introduced with the fluorescent agent Hilite Fluor is illuminated with the illumination light L ₂ having an excitation wavelength of 740 nm, the fluorescent agent Hilite Fluor specifically accumulated in the caries portion B is excited. It can be seen that bright fluorescence having a wavelength of 790 nm is detected both on the front surface and the back surface. FIG. 27 is a fluorescence image of a caries part B obtained by irradiating illumination light with a wavelength-tunable xenon light source to a specimen in which a caries part B is exposed on one surface of a molar section cut to a thickness of 1 mm. is there.

Further shows a second fluorescent image obtained by irradiating the illumination light L ₂ from the occlusal surface side in FIG. 28. According to this, there is no incidence of the second illumination light L ₂ of the direct light or reflected light, it is understood that it is possible to obtain a clear fluorescence image.

Moreover, the acquisition of the scattered light image by the first irradiation of the illumination light L _1, is performed in time division and acquiring fluorescence image by irradiation of the second illumination light L _2, first, second illumination light L ₁ and L ₂ do not affect the acquisition of other images, and noise generation in each image can be further reduced.

  As shown in FIG. 29, the dental observation apparatus 20 according to the present embodiment has tip surfaces 23a and 24a of three optical fibers 23 and 24 arranged at the tip of an insertion portion 28 inserted into the oral cavity. It is preferable to arrange the photodetector 11 at a position facing the front end surface 23a of the optical fiber 23 arranged at the foremost position with a space therebetween. In the figure, illustration of the polarizing plate and the light receiving filter is omitted. The above-mentioned observation can be performed by inserting the insertion portion 28 into the oral cavity and overcoming the tooth A and placing the tip surfaces 23a, 24a of the optical fibers 23, 24 so as to face the back side surface and the occlusal surface of the tooth A. it can.

  In the present embodiment, the optical fibers 23 and 24 are exemplified as the first and second irradiation units. However, as shown in FIG. 30, the LEDs are disposed at the positions of the front end surfaces 23 a and 24 a of the optical fibers 23 and 24. A semiconductor light source 29 such as LD or SLD may be arranged. As a result, the apparatus can be configured simply and compactly.

In the present embodiment, the first illumination light L ₁ and the second illumination light L ₂ are made different from each other. Instead, as shown in FIG. 31, the first illumination light is used. the L ₁ 700 to 800 nm, the second illumination light _{L 2} may be possible to duplicate as 750～800Nm. In this case, as the light receiving filter 10, a filter such as a filter turret or a liquid crystal filter whose transmittance characteristics can be switched is used.

For example, when the first illumination light L ₁ is irradiated, a light receiving filter 10 having a transmittance characteristic capable of transmitting the _first illumination light L ₁ is selected, and the second illumination light L ₂ is irradiated. the Rutoki, as the light receiving filter 10 blocks the second illumination light L _2, is selected to have a transmittance characteristic of transmitting fluorescence in a wavelength band of 800 to 1000 nm. Thereby, similarly to the above, a scattered light image and a fluorescence image with high contrast can be acquired, and the spread and depth of penetration of the caries portion B can be observed.

Further, as shown in FIG. 32, the first illumination light _{L 1} 600 to 750 nm, the second illumination light _{L 2} may be varying as 750～800Nm. In this case, as the light receiving filter 10, when the first illumination light L ₁ is irradiated, having a permeable transmittance characteristic first illumination light L ₁ is selected, the second illumination light When L ₂ is irradiated, a material having a transmittance characteristic that blocks the second illumination light L ₂ and transmits fluorescence in the wavelength band of 800 to 1000 nm is selected.

1 is an overall configuration diagram showing a dental observation apparatus according to a first embodiment of the present invention. It is a graph which shows the transmittance | permeability characteristic of each filter of the dental observation apparatus of FIG. It is a figure which shows an example of the fluorescence image acquired by the dental observation apparatus of FIG. It is a graph which shows the scattering characteristic of a general tooth. It is a figure which shows an example of the scattered light image acquired by the dental observation apparatus of FIG. It is a figure which shows an example of the scattered light image which processed the scattered light image of FIG. 5 and clarified the boundary of an enamel layer and a dentin layer. It is a figure which shows an example of the synthesized image which synthesize | combined the fluorescence image of FIG. 3, and the scattered light image of FIG. It is a whole block diagram which shows the 1st modification of the dental observation apparatus of FIG. It is a whole block diagram which shows the 2nd modification of the dental observation apparatus of FIG. It is a whole block diagram which shows the 3rd modification of the dental observation apparatus of FIG. It is a whole block diagram which shows the 4th modification of the dental observation apparatus of FIG. It is a whole block diagram which shows the 5th modification of the dental observation apparatus of FIG. It is a graph which shows the transmittance | permeability characteristic of each filter of the dental observation apparatus of FIG. It is a whole block diagram which shows the 6th modification of the dental observation apparatus of FIG. It is a graph which shows the transmittance | permeability characteristic of each filter of the dental observation apparatus of FIG. It is a whole block diagram which shows the 7th modification of the dental observation apparatus of FIG. It is a whole block diagram which shows the 8th modification of the dental observation apparatus of FIG. It is a graph which shows the transmittance | permeability characteristic of each filter of the dental observation apparatus of FIG. It is a whole block diagram which shows the 9th modification of the dental observation apparatus of FIG. It is a figure which shows an example of the determination of the penetration degree of the caries part by the dental observation apparatus of FIG. It is a whole block diagram which shows the dental observation apparatus which concerns on the 2nd Embodiment of this invention. It is a side view which shows arrangement | positioning of the 1st, 2nd irradiation part in the dental observation apparatus of FIG. It is a figure which shows the wavelength range of the 1st, 2nd illumination light in the dental observation apparatus of FIG. 21, and the transmittance | permeability characteristic of a light reception filter. It is a timing chart which shows the switching timing of the 1st, 2nd illumination light in the dental observation apparatus of FIG. It is a graph which shows the relationship between the wavelength of illumination light, and transparency. It is a graph which shows the relationship between the wavelength of illumination light, and autofluorescence intensity. It is a photograph which shows the chemical | medical agent fluorescence image of the caries part of (a) front surface and (b) back surface of a molar slice. It is a photograph which shows a chemical | medical agent fluorescence image at the time of making 2nd illumination light inject from an occlusal surface. It is a perspective view explaining the example of arrangement | positioning of the optical fiber in the insertion part inserted in an intraoral area. It is a perspective view explaining the example of arrangement | positioning of the semiconductor light source in the insertion part inserted in an intraoral area. It is a figure which shows the wavelength range of the 1st, 2nd illumination light in the dental observation apparatus of FIG. 21, and the modification of the transmittance | permeability characteristic of a light reception filter. It is a figure which shows the other modification of the wavelength range of the 1st, 2nd illumination light in the dental observation apparatus of FIG. 21, and the transmittance | permeability characteristic of a light reception filter.

Explanation of symbols

A tooth A ₁ enamel layer A ₂ dentin layer A ₃ boundary B caries part G ₁ fluorescence image G ₂ , G ₃ scattered light image L ₁ first illumination light L ₂ second illumination light 1,20 dental observation Device 2 Irradiation unit 3 Detection unit 4 Image processing unit 10 Light receiving filter (blocking means)
23a Tip surface (first irradiation part)
24a Tip surface (second irradiation part)
25 First polarizing plate (first polarizing member)
26 Second polarizing plate (second polarizing member)
27 Control unit (illumination light switching means)
28 Insertion Section 29 Semiconductor Light Source

Claims (13)

An irradiation unit for irradiating illumination light including an infrared region;
A detection unit that separately detects fluorescence generated from the caries portion of the tooth by irradiation of the illumination light and scattered light in the tooth of the illumination light;
Scattering that generates a fluorescence image based on the fluorescence detected by the detection unit, and that can identify the boundary between the enamel layer and the dentin layer having different scattering characteristics based on the intensity of the scattered light detected by the detection unit A dental observation apparatus comprising an image processing unit that generates a light image and combines the fluorescence image and the scattered light image.   The dental observation apparatus according to claim 1, wherein the illumination light is near infrared light.   The image processing unit compares the intensity of the scattered light acquired by the detection unit with a predetermined threshold value to generate a scattered light image that can identify the boundary between the enamel layer and the dentin layer. The dental observation apparatus according to claim 2. The irradiation unit further irradiates visible light,
The detection unit further detects the scattered light of visible light,
The image processing unit generates a visible scattered light image based on the intensity of visible light detected by the detection unit, and the boundary between the enamel layer and the dentin layer is compared with the visible scattered light image. The dental observation apparatus according to claim 1, wherein a scattered light image that can identify the image is generated.   The said image processing part gives a different color to the area | region corresponding to the caries part of the said fluorescence image, and the enamel layer and the dentin layer of the said scattered light image, and synthesize | combines them. Dental observation equipment.   From the depth level determination part which compares the distance from the surface of the said enamel layer to the said boundary, and the distance from the said caries part to the said boundary, and determines the depth of penetration of the said caries part. The dental observation apparatus according to claim 5. The irradiation unit includes a first irradiation unit that irradiates the first illumination light from the side surface side of the tooth, and a second irradiation unit that irradiates the second illumination light from the occlusal surface side of the tooth,
The dental observation apparatus according to any one of claims 1 to 6, wherein the detection unit is disposed to face the first irradiation unit with the tooth interposed therebetween.   A first polarizing member disposed between the first irradiation unit and the tooth; and a first polarizing member disposed between the tooth and the detection unit and having a polarization direction different from that of the first polarizing member. The dental observation apparatus according to claim 7, comprising two polarizing members.   The dental observation apparatus according to claim 7 or 8, wherein the second illumination light is near infrared light.   The dental observation according to any one of claims 7 to 9, further comprising a blocking unit that is disposed between the tooth and the detection unit and transmits the first illumination light and blocks the second illumination light. apparatus. Comprising illumination light switching means for switching the first illumination light and the second illumination light in a time-sharing manner;
The dental observation apparatus according to any one of claims 7 to 10, wherein the detection unit detects the fluorescence or the scattered light in synchronization with a switching timing of illumination light by the illumination light switching unit. It has an insertion part that can be inserted into the oral cavity,
The dental observation apparatus according to any one of claims 1 to 11, wherein the irradiation unit is a semiconductor light source disposed at a distal end portion of the insertion unit. The first illumination light and the second illumination light are near infrared light,
Illumination light switching means for switching the first illumination light and the second illumination light in a time-sharing manner;
A blocking means for blocking the incidence of the second illumination light on the detection unit when switched to the second illumination light by the illumination light switching means;
The dental observation device according to any one of claims 7 to 9, wherein the detection unit detects the fluorescence or the scattered light in synchronization with a switching timing of illumination light by the illumination light switching unit.

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