HK1213166B - Fluorescence filter spectrum compensation - Google Patents

Description

Spectral compensation of fluorescence filters

Technical Field

The present invention generally relates to devices and methods for examining oral structures. In particular, the present invention relates to devices and methods relating to the examination of tooth surfaces, tongue, gums, cheeks, interiors of teeth, dentures, crowns, bridges and any other oral structures by inducing autofluorescence, observing the autofluorescence through a filter, and then altering the incident light on the oral structures to compensate for the attenuation caused by the filter.

Background

In the field of dental instruments, it is understood that various devices may be used to detect abnormal and healthy tooth surfaces. In some cases, the difference between abnormal and healthy tooth surfaces may be difficult to distinguish with the naked eye. In addition to simply identifying abnormal and healthy tooth surfaces, it may be difficult for a dental health professional to determine where healthy tooth surfaces and abnormal surfaces begin.

U.S. patent No. 7,813,787 describes a dental appliance method for inspection of tooth surfaces. In particular, it describes a light source body having a handle portion. The light source body includes a switch for selectively energizing and de-energizing the blue light source. The instrument includes a yellow filter that is removable from the instrument body. The apparatus may include glasses containing a yellow filter to filter the fluorescence to be observed. However, with the disclosed instrument, the color changes when passing through the yellow filter glasses and compromises non-fluoroscopic examination of the oral cavity.

While various dental instruments have been made and used, it is believed that no one prior to the inventors has made or used the invention as described herein.

Summary of The Invention

An illustrative dental instrument is shown having a body with a handle and an arm. The dental appliance is capable of directing blue light into the oral cavity of a patient. The blue light is absorbed by porphyrins produced by living bacteria or other abnormal structures in the oral cavity and then re-emitted. The user can then look through the filter to the mouth and clearly see the porphyrin or other abnormal features revealed by the re-emitted light.

The user may then wish to view the mouth or other object in an environment under white light conditions, and may do so by turning on the second light of the dental implement without removing the filter used to visualize the anomalous features. The second light is directed through the second filter in at least some instances such that the filtered second light compensates for the first filter. Thus, the user can view the oral cavity and tooth surfaces or other objects as if under white light conditions without removing the first filter.

Brief Description of Drawings

It is believed that the invention will be better understood from the following description of certain embodiments taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:

FIG. 1 depicts a schematic view of an illustrative dental implement for use with a patient;

FIG. 2 depicts a graphical view of the transmission spectrum of the filter 22 of FIG. 1;

FIG. 3 depicts a graphical view of the relative intensity spectrum of the second LED28 of FIG. 1;

FIG. 4 depicts a graphical view of the transmission spectrum of the white light filter 26 of FIG. 1;

FIG. 5 depicts a graphical view of the relative intensity spectrum of an LED incorporating the optical characteristics of the second LED28 and the white filter 26 to transmit substantially white light through the compensating filter 22 of FIG. 1; and

fig. 6 depicts a schematic view of an alternative illustrative dental instrument for hands-free use.

These drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be practiced in various other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention; it should be understood, however, that the invention is not limited to the precise arrangements shown.

Detailed Description

The following description of certain embodiments of the invention should not be used to limit the scope of the invention. Other embodiments, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled in the art from this description. It will be understood that the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

It should be understood that in these descriptions, "visualization" refers to any method or means whereby light or images reach the human eye, whether directly or indirectly through optical elements and/or captured and displayed. The "path" taken by the light or image may likewise include one or more optical elements (lenses, mirrors, and filters, as non-limiting examples) and elements that capture, record, and/or playback images (e.g., CCDs, encoders, decoders, data transfer devices, display devices, etc.). Finally, a "substantially white spectrum" is defined as a spectrum that, when emitted to the eye, is perceived as white light.

In examining tooth surfaces or other oral surfaces or tissues in a patient's mouth, one exemplary way to visualize tooth surfaces includes using quantitative light-induced fluorescence ("QLF") to provide visualization of various aspects of abnormalities in the patient's mouth. QLF generally involves introducing light into the mouth of a patient. In many cases, the light used is strong blue light with a peak wavelength of about 405nm, but it will be appreciated that other suitable peak wavelengths may be used. Porphyrins are produced by living bacteria in the mouth. These porphyrins will fluoresce after exposure to blue light. Thus, the viable bacteria in the mouth can be visualized indirectly by observing the area of the oral cavity exposed to blue light. Visualization is improved by a lens or filter that can be manipulated to filter out a portion of the spectrum so that the porphyrin can be easily viewed through the filter. Thus, with QLF, the user can observe lesions, plaque, or any other abnormal dental condition or deposit on or in the teeth or gums.

Generally, light or blue light can be introduced into the mouth of a patient using a handheld dental instrument. The hand-held dental instruments may be operated by a dentist, health professional or other user. In addition, the handheld dental appliance may also be used in a self-examination situation, where the user uses the handheld dental appliance to view abnormal tooth surface conditions, perhaps with the aid of a mirror or other suitable tool for self-visualization. It should be understood that in some variations, the light may be applied to the oral region of the patient using a fixed instrument that may be operated manually, remotely, or otherwise by the user. While dental instruments may be used to fluoresce the regions in the mouth by exposing them to blue light, it should be understood that in order to more thoroughly view the oral cavity, a user may also wish to view the oral cavity under conditions effective to produce white light. Thus, it may be desirable for the dental tool to alternately provide blue light and compensated white light so that the user can switch between the two illumination conditions as desired without removing the filter for the QLF.

I. Exemplary dental instruments

Referring now to FIG. 1, an illustrative dental implement 10 is shown. In general, dental implement 10 may be used to emit light, such as the blue light described above, to cause the porphyrins or other related anomalies to autofluorescence. The user aligns dental implement 10 so that light shines on oral tissue, such as tooth surfaces of patient's teeth 12 in patient's mouth 11. Dental implement 10 includes a wand having a handle portion 14, with handle portion 14 connected to an arm portion 16. The arm 16 of the illustrated embodiment includes an angled rod that is capable of delivering light to the oral cavity to visualize the teeth 12 along with abnormal conditions of the teeth 12. The arm 16 may define any suitable angle relative to the axis of the handle portion 14 to properly position the arm 16 in the mouth 11. It should be appreciated that the arm 16 may comprise any shape including a straight bar, a bendable member, a knob, or any other suitable structure as would be apparent to one of ordinary skill in the art in view of the teachings herein. The handle portion 14 is shown as a cylindrical member operable to be gripped by a user. However, other suitable shapes may be used. For example, the handle portion 14 may have a contoured shape such that a user may comfortably grip the handle portion 14.

In this embodiment, the handle portion 14 of the dental implement 10 also includes a first switch 18 that can be actuated by a user. When first switch 18 is actuated, light is emitted from dental implement 10. Specifically, in the exemplary embodiment, when first switch 18 is actuated, first LED24 illuminates and transmits light through arm 16. After that, the light is emitted from the arm portion 16 into the oral cavity 11. Additionally, in the exemplary embodiment shown, the first LED24 emits blue light having a wavelength of about 405 nm. While the illustrative embodiment uses an LED for first LED24, it should be understood that first switch 18 may trigger a laser, an OLED, a light bulb, or any other light emitting structure capable of transmitting light through arm 16 and directed into oral cavity 11. In addition, the illustrated embodiment depicts the first LED24 as being located within the handle portion 14, but it should be understood that the first LED24 may also be located within the arm portion 16, on eyewear that may be worn by a user, or in any other suitable location that would be apparent to one of ordinary skill in the art in view of the teachings herein.

The arms 16 assist in directing light onto the surface of the tooth 12. Upon re-actuation of the first switch 18, the first LED24 turns off and blue light is no longer emitted from the arm 16. While the illustrative embodiment shows the first switch 18 having a button-like configuration, it should be understood that the first switch 18 may comprise a slide switch, a rotary switch, a capacitive or resistive touch switch, or any other suitable switch type. When first switch 18 is actuated and light is directed onto the surface of tooth 12, an anomalous structure or substance on the tooth may absorb the emitted blue light. Some or all of these abnormal structures or substances then auto-fluoresce with intensity peaks in the green and red range of visible light. It should be understood that structures that fluoresce spontaneously due to blue light emission may be visualized as red using the filter 22 located between the oral cavity 11 and the user's eye 30.

The filter 22 includes a bare lens, but may include glasses equipped with the filter 22. The filter 22 may be provided on a dental loupe or dental microscope. It should be understood that other means may be used to filter a particular frequency of light. In this embodiment, the filter 22 filters frequencies as shown in FIG. 2, which will be discussed in further detail below.

During use of dental appliance 10, it should be understood that a user may wish to view the surface of tooth 12 under normal white light conditions. Further, the user may wish to alternate white and blue light observations during examination of the teeth 12 in the mouth 11 without removing the filter 22 from the user's line of sight. In addition to first switch 18, which may be used to control the emission of blue light from dental implement 10, dental implement 10 includes a second switch 20 that may control the emission of "compensated white light".

In this embodiment, the second switch 20 may be actuated to illuminate the second LED28, and light filtered by the filter 26 emits light that is substantially white when viewed through the filter 22. As described above with respect to the first LED24, the second LED28 need not necessarily include an LED or include only an LED. In other exemplary embodiments, the second LED28 may alternatively or additionally include a laser, an OLED, a bulb, or any other suitable light emitting source. The second LED28 is also in optical communication with the compensating filter 26.

In the illustrative embodiment, dental implement 10 is shown with first switch 18 and second switch 20 positioned side-by-side. In fact, other suitable configurations may also be used. For example, the first switch 18 and the second switch 20 may be implemented in the form of a three-way switch or rocker to control the illumination of the second LED28 and the first LED24 in a single element. The first switch 18 and the second switch 20 may be placed in a lateral side-by-side relationship rather than a longitudinal side-by-side relationship along the length of the handle portion 14. The first switch 18 and the second switch 20 may be integrated into a touch screen or other suitable switch rather than a mechanically actuated switch. Further, the second switch 20 may be configured such that activating the second switch 20 synchronously turns on the second LED28 and turns off the first LED 24.

The compensating filter 26 is shown as a filter located between the second LED28 and the mouth 11. The compensating filter 26 is shown in the illustrative embodiment as a lens placed in front of the second LED28, but it should be understood that the compensating filter 26 may comprise other suitable variations, such as a filter lacquer, a coating covering the second LED28, or a material integrally formed with the second LED28, and still be operable to filter certain frequencies. In other variations, however, the compensating filter 26 may comprise an "optical interference filter" that intersects light emitted by the second LED28 to filter or eliminate a particular range of wavelengths. Thus, the compensating filter 26 in combination with the second LED28 can compensate for the effect of the filter 22. Thus, when the second LED28 is on, a user can view the oral cavity 11 through the filter 22 and view the interior of the oral cavity under conditions of effectively white or near-white light without removing the filter 22. This visualization may occur as the user actuates the second switch 20.

To understand the manner in which compensation filter 26 compensates for filter 22, the transmission profiles of the various filters of dental implement 10 are discussed below.

Fig. 2 depicts an illustrative graph 40 showing the transmission profile of the illustrative filter 22. In particular, horizontal axis 42 shows the various wavelengths that may reach filter 22. The vertical axis 44 shows the amount of light transmitted through the filter 22 at various wavelengths and is expressed as a percentage of transmission. Curve 46 depicts the percent transmission of light at wavelengths between 400nm and 700 nm. As can be seen from the graph 40, the filter 22 is characterized by: wavelengths between 400nm and 450nm, which is roughly the violet range of the visible spectrum, are hardly allowed to transmit through the filter 22. The filter 22 is further characterized by: has a relatively low transmission at wavelengths between 470nm and 600nm, which include the blue, green, yellow and a portion of the orange range of the visible spectrum. Finally, as the wavelength increases beyond 600nm (the orange and red portions of the visible spectrum), the light transmission through the filter 22 rises to approximately 75-80%. Thus, when blue LED24 illuminates oral cavity 11 and the user views oral cavity 11 through filter 22, the porphyrin emits light having a strong band in the low wavelength region and another strong band in the high wavelength region, but the user sees mostly the decay as bright red.

Referring now to FIG. 3, another graph 48 is shown that depicts the emission spectrum of light produced by the second LED28 (which is shown in FIG. 1) in an illustrative embodiment. The horizontal axis 52 depicts wavelengths between 400nm and 700 nm. The vertical axis 54 shows the relative intensity of the light produced by the second LED28, which is expressed as a value between 0 and 100. It can be seen from curve 50 that the relative intensity of the second LED28 peaks around 405nm (in the violet range) and has another significant intensity region in a wider band between 500nm and 600nm (mostly green and yellow).

FIG. 4 shows a graph 56 of the percent transmission of the compensating filter 26 (shown in FIG. 1) at wavelengths between 400nm and 700 nm. The horizontal axis 60 shows various wavelengths between 400nm and 700 nm. The vertical axis 62 shows the percent transmission of the compensating filter 26, which is between 0 and 100%. Curve 58 shows various transmission percentages at wavelengths between 400nm and 700 nm. It can be seen from curve 58 that there is a broad transmission band at wavelengths between 400nm and 550nm (violet, blue and green). Curve 58 then decreases around wavelengths between 600nm and 650nm (orange and red-orange) and increases transmission at wavelengths greater than 650nm (red).

The composite of graph 50 (in fig. 3, the light emitted by the second LED 28), graph 58 (in fig. 4, transmitted through the compensating filter 26), and graph 46 (in fig. 2, transmitted through the filter 22) approximates a flat spectrum. This composite view will illustrate the illumination by a combination of white light illumination approximating the oral cavity 11.

Finally, as an alternative to the second LED28 and the compensating filter 26, fig. 5 shows a compensating spectrum chart 64 representing the spectrum emitted by the filtered LED29 with built-in filter. Those skilled in the art will appreciate that filtered LED29 produces a spectral emission comparable to the combination of second LED28 and compensation filter 26 (shown in fig. 1). Similar to the graph 48 shown in fig. 3, the graph 64 is shown in relative intensity. For example, the horizontal axis 68 shows various wavelengths between 400nm and 700 nm. The vertical axis 70 shows the relative intensity of light emitted by the filtered LED 24. Curve 66 shows the relative intensity of the filtered LED24 at each of the specified wavelengths.

When comparing graph 40 of fig. 2 with graph 64 of fig. 5, it can be seen that some distortion of the color spectrum occurs when the user inspects the oral cavity using blue light seen through the transmission filter 22. The user may also wish to view oral cavity 11 as if it were illuminated with white light. Thus, a user may turn on the second LED28 while turning off the blue light to cause the second LED28 to emit light through the compensating filter 26 and into the oral cavity 11. The light emitted by the second LED28 passes through the compensation filter 26 and, therefore, compensates for the portion of the spectrum that is attenuated by the filter 22. Thus, the user can view the area of oral cavity 11 under white light conditions without removing filter 22 from his/her line of sight. This may be useful in situations where the filter 22 is not conveniently removable by being incorporated into eyewear worn by the user or in other situations where the filter 22 may not be easily removable.

Exemplary Integrated Filter and dental Instrument

It should be understood that in some instances, it may be desirable to eliminate aspects of manually operating dental instrument 10. Fig. 6 depicts an alternative version of a dental implement 110 operable to be integrated, attached, or removably attached to an eyeglass 120. While the illustrative embodiment shows the dental appliance 110 attached to the eyeglasses 120, it should be understood that the dental appliance 110 may be attached to any suitable headgear. For example, instead of eyeglasses 120, dental implement 110 may be attached to a hood, helmet, face mask, or any other suitable object as would be apparent to one of ordinary skill in the art in view of the teachings herein.

Dental implement 110 includes a first LED24 and a second LED28 with a compensating filter 26, both as previously discussed with respect to fig. 1. Dental implement 110 also includes a control box 112 and a power source 114. Control box 112 may include buttons, switches, rockers, a touch screen incorporating tactile feedback, foot pedals, or any other suitable activation device to allow a user to operate dental instrument 110 in a manner similar to dental instrument 10 shown in fig. 1. In addition, the control box 112 may be separately attached to the eyeglasses 120 as shown in the illustrative embodiment, or may alternatively be integrated with the eyeglasses 120. For example, the control box 112 may be positioned or integrated in the eyewear 120 to enable a user to easily turn on and off the first and second LEDs 24, 28 to turn on blue light and white light that is transmitted through the compensation filter 26.

Power source 114 may include a battery, an adapter to connect dental implement 110 into a standard socket, or any other suitable power source as will be apparent to one of ordinary skill in the art in view of the teachings herein. Additionally, while the illustrative embodiment shows the power source 114 and the control box 110 as separate structures, it should be understood that the power source 114 and the control box 110 may be integrated into a single device, and may also be integrated into the eyewear 120 or otherwise removably attached to the eyewear 120.

It should also be appreciated that dental implement 110 may function in a manner substantially similar to dental implement 10 of fig. 1. Because the dental appliance 110 is attached to or otherwise associated with the eyeglasses 120, the user can see the teeth 12 in the patient's mouth 11 through the filter 22 without necessarily having to hold another appliance. Furthermore, the user may then control the first LED24 and the second LED28 to view the oral cavity 11 in blue or compensated white light conditions, yet without the need to manually operate another device, thereby allowing the user to view the oral cavity 11 through the filter 22 under different illumination conditions (blue and/or white light conditions) in a hands-free or substantially hands-free manner of operation (at least with respect to the dental implement 110).

In various applications, the systems and methods described herein are applied to tooth surfaces, tongue, gums, cheeks, interiors of teeth, dentures, crowns, bridges, and any other oral structures that may occur to one of skill in the relevant art.

Exemplary procedure for Using dental instruments

Dental implement 10 may be used in a variety of ways. For example, in one exemplary method of use, dental implement 10 may be placed in proximity to oral cavity 11. The arm 16 may then be placed near or within the mouth 11. The user does not necessarily need to have an area for inspection. For example, the user may simply want to examine the entire mouth, or may focus on a particular examination region. The user grasps and moves the handle 14 to place the arm 16 in the proper position to illuminate the desired structure or area.

The user then turns on the blue light by activating the first switch 18 which illuminates the first LED 24. The first LED24 emits blue light which passes through the arm 16 and into the oral cavity 11. The porphyrin or other abnormal structure fluoresces and this fluorescence can be seen by the user's eye 30 through the filter 22. Thereafter, if the user wants to observe the inside of the oral cavity 11 or the region of the teeth 12 under the white light condition, the user activates the second switch 20. Activation of the second switch 20 extinguishes the first LED24 and illuminates the second LED28, emitting light that passes through the compensating filter 26, thereby producing compensated white light. Thus, the user can view the mouth 11 and teeth 12 without the filter as if under white light, without removing the filter 22. If the user wants to return to viewing the mouth 11 and teeth 12 under the filtered blue light, the user can again activate the second switch 20 to turn off the second LED 28. The first switch 18 may be activated again to turn off the blue light emitted by the first LED 24.

In various alternative embodiments, the filter 22 is integrated into the arm 16 or the body 14, while in other embodiments the filter 22 is separate or separable, and in other embodiments the filter 22 may be reattached. In some alternative embodiments, different light sources produce blue light and compensated white light, while in other embodiments, the two lights are produced by a single light source that may be selectively filtered and/or selectively energize one or more filaments or other light emitting structures.

While various embodiments of the present invention have been shown and described, the methods and systems described herein may be further modified by appropriate modifications by those of ordinary skill in the art without departing from the scope of the present invention. Several such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For example, the above examples, embodiments, geometries, materials, dimensions, ratios, steps, and the like are illustrative and not required. Thus, the scope of the present invention should be considered in terms of any claims that may be presented and is understood not to be limited to the details of structure and operation shown and described in this specification and the drawings.

Furthermore, the attached appendix is merely exemplary and does not necessarily limit the scope of the invention to any specific embodiment shown in the attached drawings. It should be understood that these embodiments in the attached appendix are illustrative only.

Claims (15)

1. An apparatus (10) for assisting a user in visually observing oral structures, comprising:

a first light source (24) that, when energized, emits light characterized by a first spectrum suitable for inducing tissue autofluorescence;

a first filter (22) positioned in an optical path between the tissue and the user's eye, wherein light emitted by healthy tissue is more visually distinguishable from light emitted by non-healthy tissue after passing through the first filter (22); and

a second light source (28) that, when energized, emits light characterized by a second spectrum (66), wherein the light characterized by the second spectrum (66) has a substantially white spectrum after passing through the first filter (22).

2. The device of claim 1, further comprising a light detector in the path from the first filter (22) to the user's eye.

3. The device of claim 1, wherein there is no photodetector in the path from the first filter (22) to the user's eye.

4. The apparatus of claim 1, wherein the second light source comprises a second filter (26).

5. The apparatus of claim 1, wherein the second light source comprises a supplemental light source.

6. The apparatus of claim 1, wherein energizing the second light source (28) de-energizes the first light source (24).

7. A method of viewing oral structures comprising the steps of:

energizing a first light source (24) to emit light characterized by a first spectrum suitable for inducing tissue autofluorescence;

observing the tissue through a first filter (22) located in an optical path between the tissue and the user's eye, wherein induced autofluorescence of healthy tissue is more visually distinguished from induced autofluorescence of non-healthy tissue after passing through the first filter (22); and

energizing a second light source (28) to emit light characterized by a second spectrum (66), wherein the light characterized by the second spectrum (66) has a substantially white spectrum after passing through the first filter (22).

8. The method of claim 7, further comprising detecting an image including the autofluorescence after the autofluorescence passes through the first filter (22) using a light detector.

9. The method of claim 8, further comprising displaying the image.

10. The method of claim 8, further comprising storing the image.

11. The method of claim 7, further comprising:

capturing a first video in substantially real-time while the first light source is energized, wherein the first video comprises a plurality of images of the autofluorescence after the autofluorescence passes through the first filter (22); and

capturing a second video in substantially real-time while the second light source is energized, wherein the second video comprises a plurality of images of the tissue.

12. The method of claim 7, wherein there is no photodetector in the path from the first filter (22) to the user's eye.

13. The method of claim 7, wherein the second light source comprises a second filter.

14. The method of claim 7, wherein the second light source comprises a supplemental light source.

15. The method of claim 7, wherein energizing the second light source substantially simultaneously de-energizes the first light source.