WAVELENGTH AND BANDWIDTH SELECTION FOR DIFFUSE REFLECTIVE SPECTROSCOPY BASED GINGIVITIS DETECTION

Abstract

A system (100) for detecting tissue inflammation, and gingivitis specifically, including a light emitter (102); a diffuse reflective spectroscopy probe (107) having a source-detector distance between 300 μm-2000 μm; and a plurality of detectors (106, 108, 112) configured to detect: a first wavelength that is less than 615 nm and having a first bandwidth; and second and third wavelengths that are equal to or greater than 615 nm and have second and third bandwidths, respectively, wherein the second or third bandwidth is greater than the first bandwidth.

Claims

1. A system for detecting inflammation in tissue, comprising: a light emitter; a diffuse reflective spectroscopy probe having a source-detector distance between 300 μm-2000 μm; and a plurality of detectors configured to detect: a first wavelength that is less than 615 nm and having a first bandwidth; and at least second and third wavelengths that are equal to or greater than 615 nm and have second and third bandwidths, respectively, wherein said at least second or third bandwidth is greater than said first bandwidth.

2. The system of claim 1, wherein said light emitter is configured to deliver light to gingival tissue and said plurality of detectors is configured to detect diffuse reflected light from the gingival tissue.

3. The system of claim 1, further comprising: a spectral analysis unit configured to receive and analyze detected diffuse reflected light, said spectral analysis unit comprising a splitter configured to distribute the detected light over the plurality of detectors.

4. The system of claim 3, further comprising: a controller comprising an inflammation detection unit, said controller configured to receive input from each of the plurality of detectors for detecting tissue inflammation.

5. The system of claim 1, wherein said at least second or third bandwidths are at least 50% greater than said first bandwidth.

6. The system of claim 1, wherein said at least second or third bandwidth is 100% greater than said first bandwidth.

7. The system of claim 1, wherein said at least second or third bandwidth is 100%-400% greater than said first bandwidth.

8. The system of claim 1, wherein the plurality of detectors is configured to detect at least a fourth wavelength that is greater than 615 nm, wherein said at least fourth wavelength bandwidth is greater than said first second and third bandwidths.

9. A system for detecting tissue inflammation, comprising: a plurality of light emitters; a diffuse reflective spectroscopy probe having a source-detector distance between 300 μm-2000 μm; and a detector configured to detect: a first wavelength that is less than 615 nm and having a first bandwidth; and at least second and third wavelengths that are equal to or greater than 615 nm and have second and third bandwidths, respectively, wherein said second or third bandwidth is greater than said first bandwidth.

10. The system of claim 9, wherein said plurality of light emitters is configured to deliver light to gingival tissue and said detector is configured to detect diffuse reflected light from the gingival tissue.

11. The system of claim 9, wherein said plurality of light emitters are configured to deliver light to a light combiner which is configured to combine the emitted light and deliver the combined light to gingival tissue.

12. The system of claim 9, wherein said at least second or third bandwidth is at least 50% greater than said first bandwidth.

13. The system of claim 9, wherein said at least second or third bandwidth is 100% greater than said first bandwidth.

14. The system of claim 9, wherein said at least second or third bandwidth is 100%-400% greater than said first bandwidth.

15. The system of claim 9, wherein the detector is configured to detect at least a fourth wavelength that is greater than 615 nm, wherein said at least fourth wavelength bandwidth is greater than said first second and third bandwidths.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0027] FIG. 1 is a graph representing a diffuse reflective spectroscopy spectrum measured from a healthy gingiva.

[0028] FIG. 2 is a graph representing absorption spectra of oxygenated and deoxygenated hemoglobin.

[0029] FIG. 3 is a graph representing wavelength-dependent sampling depth using 200 μm fibers for different source-detector distances.

[0030] FIG. 4 is a schematic representation of a system for detecting tissue inflammation, in accordance with an embodiment.

[0031] FIG. 5 is a schematic representation of a system for detecting tissue inflammation, in accordance with an embodiment.

[0032] FIG. 6 is a schematic representation of a diffuse reflective spectroscopy probe, in accordance with an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0033] The present disclosure describes various embodiments of systems and methods for improved detection of tissue inflammation, and gingivitis specifically, using commercially available light-emitting diodes (LEDs) and diffuse reflective spectroscopy (DRS). More generally, Applicant has recognized and appreciated that it would be beneficial to provide an optimized wavelength selection for DRS-based gingivitis detection using wavelengths within the visible spectrum. Accordingly, the systems and methods described or otherwise envisioned herein provide an oral healthcare device configured to obtain measurements of gingival tissue. The oral healthcare device includes a light emitter using commercially available lighting LEDs, a DRS probe, and detectors for spectral analysis.

[0034] The embodiments and implementations disclosed or otherwise envisioned herein can be utilized with any suitable oral healthcare device. Examples of suitable oral healthcare devices include a toothbrush, a flossing device, an oral irrigator, a tongue cleaner, or other personal care device. However, the disclosure is not limited to these oral healthcare devices, and thus the disclosure and embodiments disclosed herein can encompass any oral healthcare device.

[0035] Gingivitis, which is an inflammation of the gums, characterized by swollen gums, edema, and redness, is primarily caused by plaque build-up, mostly in the gingival sulcus (pockets). Such gum disease is typically found in areas that are hard to reach, such as interproximal areas between the teeth, and around the back teeth.

[0036] Indeed, it is estimated that 50%-70% of the adult population is affected by gingivitis. However, consumers are often unable to detect early signs of gingivitis. Typically, gingivitis progresses until individuals notice their gums bleeding easily when brushing their teeth. Accordingly, gingivitis may only be detected when the disease is already advanced and significantly harder to treat. Although gingivitis is readily reversed by improved oral hygiene, as gingivitis can propagate to irreversible periodontitis it is important to keep good oral health and detect gingivitis as soon as possible.

[0037] Gingivitis may be visually diagnosed by detecting reddening and swelling of the gingiva. (See RR. Lobene, et al., “A modified gingival index for use in clinical trials”, Clin. Prev. Dent. 8:3-6, (1986) describing a non-contact gingivitis index, based on reddening and inflammation of the gingiva). However, this has limited sensitivity and is highly dependent on the color rendering index of the light-source used. Thus, modern phosphor-converted LEDs can have a low CRI resulting in poor visual judgments.

[0038] FIG. 1 shows an example of a diffuse reflective spectroscopy (DRS) spectrum measured from a healthy gingiva 1, the bottom (dotted) line in the chart, which shows the measurement that includes hemoglobin (blood) and melanin. Also shown are the scattering component 2, the top line in the chart, which is the component that enables the diffuse reflectance (i.e. without it, no light would be diffusely reflected/returned). Line 3 (the middle line in the chart) shows the absorption component due to melanin 3 which is one of the main absorbing chromophores in gingival tissue. The hemoglobin-dominated region is best suited for determining an amount of the DRS signal originating from blood.

[0039] The influence of hemoglobin absorption is apparent when looking at FIG. 2. Some of the other main absorbing chromophores are hemoglobin: especially oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb). The absorption spectra of these two chromophores are clearly shown in FIG. 2.

[0040] The reddening of the gingiva is an acute inflammatory response to bacterial biofilm toxins from plaque in the gingivae sulcus or regions along the gum line. This inflammatory response in the short term causes vasodilation, where smooth muscle cells in the arterioles relax, and widen the blood vessels to increase blood supply to the capillary bed. This gives the reddening of the gingiva, and can give a small temperature increase, which is difficult to measure. In addition, the capillaries become more permeable, which results in increased fluid loss from the capillaries to the interstitial spaces, resulting in the swelling of the gums. If the inflammation is chronic, then additional reddening occurs by increased vascularization of the tissue, where additional capillaries may be formed to cope with the additional blood demands of the tissue.

[0041] These factors enable detection of gingivitis based on diffuse reflective spectroscopy (DRS). DRS is an optical method that involves emitting, for example, white light towards a target and analyzing spectral properties of the diffuse (rather than specular) reflected light. DRS probe configurations consist of one source fiber next to one detection fiber, one central source fiber surrounded by a plurality of detection fibers, or a single fiber functioning as source and detector simultaneously. An important property of the probe is the source-detection separation because it influences the sampling depth of the probe (i.e., from how deep in the tissue the measured light originates). To detect gingivitis, an average diffuse reflective spectroscopy sampling depth that is greater than 250 μm is required. To obtain such an average, a minimum source-detector distance of approximately 300 μm is required, depending on wavelength. However, such sampling depth cannot be achieved with blue light due to the high absorption in hemoglobin. FIG. 3 shows wavelength-dependent sampling depths (250 μm to 1000 μm) for different source-detector distances. Moreover, all gingivae are not equal and in some individuals the sampling depth may need to be deeper, thus, different wavelength(s) and/or probe designs may be required.

[0042] A particular goal of utilization of certain embodiments of the present disclosure is to enable accurate gingivitis detection with diffuse reflective spectroscopy signals using a minimum number of wavelengths and commercially available phosphor-converted (PC) light-emitting diodes (LEDs).

[0043] Referring to FIG. 4, in one embodiment, is a tissue inflammation detection system 100. System 100 includes a light emitter 102 using commercially available lighting LEDs. The inventive systems described herein use commercially available lighting LEDs because they are inexpensive and efficient. Thus, the available wavelength range is typically from to 500 nm-780 nm. System 100 also includes a diffuse reflective spectroscopy (DRS) probe 107 (shown in FIG. 6) having a source-detector distance d between 300 μm-2000 μm. The source fiber 101 is configured to be supplied with light from a light source, such as, phosphor-converted LEDs, and deliver such light to tissue 104. The detector fiber 103 is configured to pick up diffuse reflected light from tissue 104 and deliver this light to spectral analysis unit 105. As shown in FIG. 6, the DRS probe 107 consists of one source fiber 101 and one detection fiber 103, however, other suitable configurations are contemplated in accordance with the embodiments described herein. For example, in an embodiment including more than one detector fiber, the outputs from each fiber should be combined together, and the single resulting signal should be delivered into spectral analysis unit 105 where the signal is distributed over the wavelength-sensitive detectors.

[0044] According to an embodiment, the spectral analysis unit 105 is a splitter configured to distribute the received diffuse reflected light over n wavelength-sensitive photodetectors (e.g., bandpass filter+photodiode) 106, 108, 110, and 112. The spectral analysis unit 105 can include a fused fiber splitter, a dispersive splitter (e.g. prism or grating), a light guide manifold, or any suitable alternative. Detector 106 is configured to be sensitive to λ1 having a specific full width at half maximum (FWHM1). Detector 108 is configured to be sensitive to λ2 having FWHM2. Detector 110 is configured to be sensitive to λ3 having FWHM3. Detector 112 is configured to be sensitive to λ4 having FWHM4. The output of each wavelength-sensitive photodetector is input to a controller 113 having an inflammation detection unit 114. The inflammation detection unit 114 can include an algorithm which can be based on any mathematical equation on these inputs. According to an embodiment, a spectrometer or a tunable filter can also be used as a spectral detector. However, these are currently considered too expensive and/or bulky for a consumer product.

[0045] According to an example embodiment including four wavelengths, detector 106 is sensitive to λ1 where λ1=575 nm-585 nm, preferably 580 nm, and FWHM1=10 nm; detector 108 is sensitive to λ2 where λ2=589 nm-599 nm, preferably 594 nm, and FWHM2=10 nm; detector 110 is sensitive to λ3 where λ3=670 nm-680 nm, preferably 675 nm, and FWHM3≥10 nm; and detector 112 is sensitive to λ4 where λ4=695 nm-705 nm, preferably 700 nm, and FWHM4≥15 nm, preferably 20-50 nm.

[0046] According to another example embodiment including five wavelengths, detector 106 is sensitive to λ1 where λ1=575 nm-585 nm, preferably 580 nm, and FWHM1=10 nm; detector 108 is sensitive to λ2 where λ2=589 nm-599 nm, preferably 594 nm, and FWHM2=10 nm; detector 110 is sensitive to λ3 where λ3=670 nm-680 nm, preferably 675 nm, and FWHM3≥10 nm; detector 112 is sensitive to λ4 where λ4=689 nm-699 nm, preferably 694 nm, and FWHM4≥10 nm; and an additional detector (not shown) that is sensitive to λ5 where λ5=715 nm-725 nm, preferably 720 nm, and FWHM5≥15 nm, preferably 20-50 nm.

[0047] According to another example embodiment including five wavelengths, detector 106 is sensitive to λ1 where λ1=570 nm-580 nm, preferably 575 nm, and FWHM1=10 nm; detector 108 is sensitive to λ2 where λ2=625 nm-635 nm, preferably 630 nm, and FWHM2=10 nm; detector 110 is sensitive to λ3 where λ3=669 nm-679 nm, preferably 674 nm, and FWHM3≥10 nm; detector 112 is sensitive to λ4 where λ4=737 nm-747 nm, preferably 742 nm, and FWHM4≥10 nm; and an additional detector (not shown) that is sensitive to λ5 where λ5=765 nm-775 nm, preferably 770 nm, and FWHM5≥15 nm, preferably 20 nm.

[0048] Any of the specific wavelength selections described above can be incorporated into embodiments where the spectral diversity is provided by wavelength-specific emitters rather than wavelength-sensitive detectors. As shown in FIG. 5, an inflammation detection system 200 is shown including four wavelength-specific emitters 202, 204, 206, and 208 configured to be supplied with light from LEDs having the desired spectral properties and/or modified properties by application of, e.g., bandpass filters. Emitter 202 is associated with λ1 and FWHM1. Emitter 204 is associated with λ2 and FWHM2. Emitter 206 is associated with λ3 and FWHM3. Emitter 208 is associated with λ4 and FWHM4. Like system 100, system 200 can include additional emitters associated with additional wavelengths and bandwidths. Light from the four wavelength-specific emitters is delivered to light combiner 205 or any suitable alternative. Like system 100, system 200 includes a diffuse reflective spectroscopy (DRS) probe such as the one depicted in FIG. 6 having a source-detector distance between 300 μm-2000 μm. The detector fiber 103 is configured to pick up diffuse reflected light from tissue 204 and deliver this light to a controller 213 having an inflammation detection unit 214. The inflammation detection unit 214 can include an algorithm which can be based on any mathematical equation on these inputs.

[0049] Advantageously, the inventive systems enable accurate gingivitis detection using a minimum number of wavelengths and commercially available phosphor converted (PC) light-emitting diodes (LEDs).

[0050] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

[0051] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0052] The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified.

[0053] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.”

[0054] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified.

[0055] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0056] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively.

[0057] While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.