Abstract:
Described are dental implements useful for inspecting tooth surfaces for abnormalities such as caries or plaque. Preferred implements of the invention include light emitting diodes mounted on an implement body having a mirror for insertion into a user&#39;s mouth. Such implements also have on-board batteries mounted in chambers in the implement handle, and a switch for energizing and de-energizing the LED with the battery. Also described are methods for examining tooth surfaces for abnormal conditions indicative of plaque involving illuminating surfaces with radiation at a wavelength in the range of 390-450 nm wherein the radiation is effective to cause detectable fluorescence emissions from bacterial metabolites known to be associated with plaque-containing surfaces, and detecting the emissions.

Description:
BACKGROUND 
     The present invention relates generally to devices and methods for inspecting tooth surfaces, and in particular to such devices and methods involving the detection of differential fluorescence emissions from abnormal and healthy tooth surfaces. 
     As further background, various devices and methods have been proposed that involve using fluorescence emissions to detect caries or other abnormal conditions. For example, U.S. Pat. No. 3,711,700 relates to a disclosing light for inspecting tooth surfaces. The disclosing light is designed for use in conjunction with a fluorescent dye such as sodium fluorescein. The disclosing light includes a light source and a dichroic reflector behind the light source to reflect blue light forward and the remainder backward. A second dichroic filter is positioned in front of the light source and transmits blue light and reflects back infrared radiation. A mirror reflects yellow light to the observer and transmits other wavelengths. 
     U.S. Pat. No. 4,266,535 discloses a diagnostic lamp for use in conjunction with a fluorescent dye to inspect tooth surfaces. The lamp includes an incandescent bulb light source used in conjunction with a lens to supply a divergent beam of rays. A blue filter with an applied dichroic filter is used to filter the rays, which are made to impinge upon the fluorescent dye. The resulting fluorescence can be viewed in a folding, adjustable mirror. U.S. Pat. No. 5,957,687 discloses another diagnostic unit including a filtered light source and a mirror contained in a housing. Filtered light is concentrated in the blue frequency range and causes fluorescent dye to fluoresce. This can then be viewed in the mirror. 
     U.S. Pat. No. 4,290,433 discloses a method and device for detecting caries in human teeth using luminescence. The luminescence from teeth is measured at two predetermined wavelengths, one of which is about the same for caries-containing and non-caries-containing surfaces, and another where the luminescence is higher for caries-containing surfaces. A signal is generated corresponding to the difference in the intensities at the two measured wavelengths. A baseline measurement is taken at a non-decayed region, and the probe is then directed to other regions to assess the presence or absence of caries. 
     U.S. Pat. No. 4,515,476 describes a device for the ocular determination of discrepancies in the luminescence capacity of tooth surfaces. The disclosed device includes an argon laser for generating visible light in a predetermined wavelength range that causes luminescence from tooth surfaces. An absorption filter is used to eliminate reflections and luminescence within the predetermined wavelength range of the laser light. In this fashion, unsound tooth surface areas such as caries can be viewed as dark areas. 
     U.S. Pat. No. 5,894,620 discloses an electric toothbrush with means for locating dental plaque. The electric toothbrush includes an optical fiber for transmitting excitation radiation to tooth surfaces, and an optical fiber(s) for receiving a return luminescence or fluorescence signal. The return signal is then processed to activate a light or audible signal indicative of the presence of plaque. 
     In light of this background, there remain needs for improved, convenient devices and methods for tooth surface inspection to detect caries and other surface abnormalities. The present invention is addressed to these needs. 
     SUMMARY OF THE INVENTION 
     Accordingly, in one embodiment, the invention provides a hand-held dental implement for use in detecting abnormal tooth surface conditions. The dental implement includes an implement body having a proximal handle connected to a distal end, and a mirror mounted on the distal end and adapted for insertion into the mouth of the user. The proximal handle defines a battery chamber for receiving a battery. The battery chamber has a positive electrical connection and a negative electrical connection for electrical contact with respective positive and negative terminals of the battery. At least one light emitting diode is mounted on the implement and has positive and negative leads electrically connected to the positive electrical connection and said negative electrical connection, respectively, so as to be energizable by the battery. The light emitting diode is effectively positioned on the implement to illuminate tooth surfaces of the user when the mirror is positioned in the mouth of the user, and is effective to emit radiation that causes visually detectable differential fluorescence emissions from normal tooth surfaces and abnormal tooth surfaces. A switch is provided on the implement and has a first condition wherein the light emitting diode is energized by the battery, and a second condition wherein the light emitting diode is not energized by the battery. In one embodiment, the light emitting diode is adapted to emit light having a peak intensity in the wavelength range of about 390 nm to about 500 nm. In another embodiment, the implement includes a light filter positioned to filter the differential fluorescence emissions for direct visualization by the user. 
     Another embodiment of the invention provides a hand-held dental implement for detecting abnormal tooth surface conditions. The dental implement includes a handle having a proximal end and distal end, and a battery chamber is present in the handle for receiving a battery. A light source is mounted on the implement and is electrically connected to the battery chamber, wherein the light source is energizable by a battery received in the battery chamber. The light source is adapted for insertion into the mouth of a user and effective to illuminate tooth surfaces sufficiently to cause visually detectable differential fluorescence emissions from normal tooth surfaces and abnormal tooth surfaces. A filter is included with the implement and is positioned to filter the fluorescence emissions for direct visualization by the user. The light source is desirably adapted to emit light having a peak intensity in the wavelength range of about 390 nm to about 500 nm, and in one embodiment in the peak intensity is in the wavelength range of 390 nm to about 450 nm. In this lower wavelength range, fluorescence emissions can be directly visualized to detect both carious surfaces (yellow-green emissions) and surfaces containing or covered with bacterial metabolites associated with plaque (red-orange emissions). 
     Another embodiment of the invention provides a method for examining tooth surfaces for abnormal surface conditions. The method includes illuminating the tooth surfaces with light from a light emitting diode having a peak intensity in the wavelength range of about 390 nm to about 500 nm, wherein the illuminating is effective to cause visually detectable differential fluorescence emissions from normal tooth surfaces and abnormal tooth surfaces. Fluorescence emissions from the normal and abnormal tooth surfaces are filtered and the differential fluorescence emissions are visually detected. 
     In another embodiment, the invention provides an apparatus for examining tooth surfaces for abnormal surface conditions. The apparatus includes a light emitting diode adapted when energized to emit radiation having a peak intensity in a wavelength range from 390 nm to 500 nm, wherein the emitted radiation is effective to cause detectable differential fluorescence emissions from normal tooth surfaces and abnormal tooth surfaces. Means for energizing the diode are provided, along with at least one filter for filtering the fluorescence emissions to facilitate detection of the differential fluorescence emissions. 
     A still further embodiment of the invention provides a method for detecting plaque-containing surfaces in the oral cavity (including areas such as tooth surfaces, gums, in inter-proximal areas, in tooth fissures, or in caries lesions). The method includes illuminating areas of the oral cavity with radiation having a peak intensity at a wavelength in the range of 390 nm to 450 nm, wherein the radiation is effective to cause detectable fluorescence emissions from bacterial metabolites known to be contained within plaque. The fluorescence emissions are then detected. 
     The present invention provides improved and alternative implements, apparatuses and methods for inspecting tooth surfaces for abnormalities such as caries or bacterial metabolites potentially indicative of plaque. Additional embodiments as well as features and advantages of the invention will be apparent to those of ordinary skill in the art from the descriptions herein. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  provides a perspective view of one embodiment of an inventive dental implement for inspection of tooth surfaces. 
         FIG. 2  provides a perspective view of an alternative embodiment of a dental implement for tooth inspection having a yellow filter mounted on the implement body. 
         FIG. 3  provides a perspective view of an alternative embodiment of a dental implement for tooth inspection having light sources mounted in a mirror housing. 
         FIG. 4  is a perspective view of an alternative embodiment of a dental implement having both blue and white light sources mounted on the implement body. 
         FIG. 5  provides a perspective view of an alternative embodiment of a dental implement having blue and white light sources mounted in a mirror housing. 
         FIG. 6  provides a perspective view of an alternative embodiment of a dental implement having detachable filter and mirror components. 
         FIG. 7  provides a perspective view of another dental implement of the invention having a detachable mirror component. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to certain embodiments thereof and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiment, and any further applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates are also included. 
     As disclosed above, one embodiment of the present invention provides a hand-held dental implement for use in detecting abnormal tooth surface conditions. Generally, such dental implements of the invention incorporate components enabling the use of Quantitative Light-induced Fluorescence or “QLF” to provide direct visualization of areas having incipient caries lesions, plaque, stains or other abnormal tooth surface conditions or deposits. Such devices can be used to conduct self-examinations or examinations of others in household or clinical settings. 
     Referring now to  FIG. 1 , an illustrative dental implement of the invention is shown. In particular, shown is a dental implement  11  useful for inspecting tooth surfaces to detect abnormal conditions. Dental implement  11  generally includes an implement body having a handle portion  12  connected to a mirror portion  13  through a transitional portion  14 . Transitional portion  14  may be contoured to position the mirror portion  13 , and in particular the face of mirror  15 , at an angle relative to the axis of handle portion  12 , so as to facilitate proper positioning of mirror  15  for viewing tooth surfaces. Mirror  15  may be circular or oval as shown or may have any other suitable shape for insertion into the mouth of a user. Mirror portion  13  includes a mirror housing  16  surrounding and mounting the mirror  15 . Dental implement  11  also includes a blue light source  17  mounted on the implement  11 , and in the illustrative embodiment mounted within the transitional portion  14  of the implement body. Blue light source  17  is preferably adapted to emit light having a peak intensity in the wavelength range of about 390 nm to about 500 nm, more desirably in the wavelength of about 390 nm to about 450 nm. Blue light source  17  advantageously includes a light emitting diode having the described characteristics. The light emitting diode may or may not have a collimator optical system integrated therein. Suitable light emitting diodes for these purposes are commercially available from Cree, Inc., under product codes C405-XB900-x and C405-MB290E400. Blue light emitting diodes having a peak wavelength of about 405 nm have been particularly advantageous in work to date. 
     Dental implement  11  also includes an on-board battery  18  mounted within a housing  19  defined by the body of implement  11 , and in the illustrated device defined within the handle portion  12  of the body of implement  11 . Access to the housing  19  may be provided, for example, by a cap  20  threadable onto the end of handle portion  12  of the implement body. Other access means may also be provided. Battery housing  19  includes a positive battery contact  21  and a negative battery contact  22  for contacting positive and negative terminals of battery  18 , respectively. Positive battery contact  21  is electrically connected to positive wire  23  and negative battery contact  22  is connected to negative wire  24 . Wires  23  and  24  and other components of the electrical system are preferably housed within the implement body  11 . Positive wire  23  is connected to a positive lead of the light emitting diode  17  or other light source and negative wire  24  is connected to a negative lead of the light emitting diode  17  or other light source. The battery  18  may be replaceable or may be rechargeable. In the latter case, the implement  11  may be provided and electrically matable with a recharging stand or other recharging instrument adapted to be plugged into an electrical outlet in a home or office. Likewise, in another inventive embodiment, a dental implement similar to implement  11  could itself be adapted to be plugged into and powered from such an electrical outlet. 
     A switch  25  for energizing and de-energizing the light source  17  with the battery is provided. Switch  25  may be any suitable switch for these purposes including vertically-displaceable push-button switches, or horizontally-displaceable slide switches. Further, other switching mechanisms may be built into the device including, for example, inertial switches optionally in combination with appropriate circuitry for energizing the light source  17  for a predetermined period of time upon actuation of the inertial switch. These and other switches will be recognized as useful in the present invention by those of ordinary skill in the art. 
     Dental implement  11  also includes an opaque or other suitable shield  26  for shielding blue light emitted by blue light source  17  and preventing such blue light from direct visualization by a user of dental implement  11 , which could possibly corrupt visualization of the desired fluorescence signal. To this end, shield  26  will be mounted proximal to the blue light source  17  to prevent direct visualization of the emitted blue light by a user of the implement  11 . 
     Dental implement  11  also includes a light filter  27  for filtering light. For use in the invention, filter  27  may, for example, filter light based upon wavelength or based upon polarization. When a wavelength-based filter is used, it is preferable that the light source  17  emit no significant amount of light above the cut-off wavelength of the filter. For example, when using a blue light source with an intensity peak in the wavelength range of 390 nm to 450 nm, it is desirable to use a yellow filter with a cutoff of about 520 nm. When using polarization as a means for the filter, the optical filter desirably will eliminate all polarized light originating from the illuminated area as the fluorescence signal will be randomly polarized. In the illustrated embodiment, light filter  27  is coated or layered onto the surface of the mirror  15 . 
     In use of the dental implement  11 , when the mirror portion  13  is inserted into the mouth of a user with the mirror  15  positioned to view tooth surfaces, and blue light source  17  is energized, tooth surfaces will be impinged by the blue light from the blue light source  17  and caused to fluoresce in the green wavelength range. Such green fluorescence from healthy and unhealthy tooth surfaces will pass through the yellow filter  27  prior to visualization by the user. Potentially corruptive light from the source  17  and fluorescence at wavelengths below the cut-off for the filter  27  will not pass through the filter  27 . Because fluorescence from carious tooth surfaces in the green spectrum is less intense than that from healthy tooth surfaces, carious tooth surfaces will appear as dark areas or patches visible to the user of the dental implement  11 . 
     With reference now to  FIG. 2 , shown is another dental implement  31  in accordance with the present invention. Dental implement  31  has similar components to dental implement  11  ( FIG. 1 ), except implement  31  has no yellow filter coated onto mirror  15 , but rather has a yellow filter  24 A mounted on the implement body and in particular on the transitional portion  14  thereof. In this fashion, again, potentially corruptive reflected light and fluorescence emissions will not pass through yellow filter  24 A, whereas fluorescence emissions in the green spectrum will pass and be visualized by a user of implement  31  revealing caries lesions as dark areas. Yellow filter  24 A can be of circular or oval shape as shown, or of any other suitable shape. Yellow filter  24 A is generally sized and positioned to enable visualization of light reflecting from mirror  15  and through yellow filter  24 A. 
     With reference now to  FIG. 3 , shown is another dental implement of invention  41  having an alternative light source configuration. Implement  41  has features similar to those of implement  31  ( FIG. 2 ), except implement  41  has multiple light sources  17 A housed within the mirror portion  13  and in particular housed circumferentially within the mirror housing  16  surrounding the mirror  15 . Light sources  17 A may, for example, be a plurality of blue LEDs as described hereinabove. 
     Referring now to  FIG. 4 , shown is an alternative dental implement  51  of the invention having features similar to those of dental implement  31  ( FIG. 2 ), except having a white light source  52  in addition to the blue light source  17 . In dental implement  51 , the switch  25  is a three-position switch for selectively energizing the blue light source  17 , the white light source  52 , or de-energizing both light sources  17  and  52 . Dental implement  51  thus enables a selection by the user between fluorescence-based visualization and normal reflected white-light visualization. This assists the user in differentiating among caries-containing tooth surfaces and stained tooth surfaces, both of which can appear as dark areas in the fluorescence-based visualization. 
       FIG. 5  shows another dental implement  61  according to the present invention. Implement  61  includes both blue light sources  17 A and white light sources  62  similar to prior-discussed implement  51  ( FIG. 4 ), except having the light sources mounted in the mirror housing  16  in a fashion similar to implement  41  ( FIG. 3 ). Switch  25  and implement  61  thus is a three-position switch for selectively energizing the plurality of white light sources  62 , the plurality of blue light sources  17 A, or for de-energizing all light sources. 
     Referring now to  FIG. 6 , disclosed is another dental implement  71  according to the present invention. Implement  71  includes a light source body  72  including a handle portion  73  defining a battery chamber for receiving a battery similar to the corresponding components in implement  11  ( FIG. 1 ). Implement body  72  includes a switch  74  for selectively energizing and de-energizing a blue light source  75  with a battery housed in the housing. Implement  71  also includes a yellow filter  76  that is detachable from the implement body  72 , for example, having a cut-out portion  77 A adapted to mate with a groove  77 B in implement body  72  to achieve a friction or snap fit of the filter  76  to the body  72 . Implement  71  also includes a detachable mirror unit  78  having a mirror  79 , a stem  80  portion, and an attachment portion  81  adapted for friction or snap fit with the implement body  72 . Such separate components may be sold together in a kit for assembling the dental implement. In addition to, or as an alternative to, attachable filter  76 , dental implement  71  or kits for the same may include glasses  82  or other devices adapted to be worn over the eyes, containing a yellow filter(s) for filtering fluorescence to be viewed. In implement  71 , blue light source  75  is advantageously located at or near the tip of the implement body  72  for effective illumination of tooth surfaces with the blue light source (e.g., LED). As well, the detachable mirror unit  78  may be attached to the implement body  72  at varying positions thereby providing flexibility in the configuration of the mirror  79  relative to the handle portion  73 , so as to enable user optimization of tooth visualization. 
     With reference now to  FIG. 7 , shown is another alternative dental implement  91  of the invention. Dental implement  91  includes an implement body  92  having a switch  93  for energizing and de-energizing a light emitting diode  97  with a battery (not shown) located within the body  92 . Implement body  92  includes a generally curved handle portion  94  connected to a transitional portion  95  which may be integral with handle portion  94 , or as shown may be a separate piece  95  connected to handle portion  94 . Transitional portion  95  terminates in a generally cone-shaped terminus  96  defining a concave inner surface, optionally made of or coated with a reflective material, and within which is located a blue light emitting diode  97 . Light emitting diode  97  may be any one of those identified above. Dental implement  91  further includes a mirror unit  98  connectable to implement body  92  by a snap or friction fit. Mirror unit  98  further includes a mirror surface  99 . Mirror unit  98  is adapted so that when attached to implement body  92 , light emitted by the diode  97  reflects from the mirror surface  99  and on to the oral cavity (e.g. tooth) surfaces to be viewed. The fluorescence signals from the surface are then reflected back onto and from mirror surface  99  for visualization by a user (the mirror unit  78  and implement body  72  of implement  71 ,  FIG. 6 , can be adapted to similarly direct the paths of the light source and fluorescence signals). Implement  91  can be used in conjunction with a yellow filter positioned to filter the fluorescence signals reflected from mirror surface  99  prior to viewing. The yellow filter can be in the form of goggles (e.g. item  82 ,  FIG. 6 ), a separate filter portion mounted on implement body  92  (e.g. such as item  76 ,  FIG. 6 ), a filter adapted to be mounted on another mirror surface in the proximity of the user (e.g. a bathroom mirror), or the like. 
     Additional aspects of the present invention relate to the discovery that when more energetic (shorter wavelength) blue light is utilized, metabolic products of bacteria that typically reside in plaque, tarter, gingiva (pockets), dental tissue (lesions, cavities, cracks) and unpolished restorative materials (leaks around fillings, unpolished restorative surfaces, and cracks in restorative materials), will be cause to emit visually detectable red to orange fluorescence (about 500 nm to about 700 nm). In particular aspects, orange to red fluorescence (in the range of about 590 nm to about 700 nm) is emitted by porphyrin materials that are produced primarily by anaerobic bacteria linked to gingivitis and extracellular or intracellular polysaccharides (linked to consumption of sugars such as glucose and saccharose). Preferred excitation radiation for these purposes falls within the wavelength range of about 390 nm to about 450 nm. In certain embodiments of the invention, the detection of the red to orange fluorescence is to be used in conjunction with the dental implements, apparatuses and methods described above. Detection of the red to orange fluorescence can also be used in other systems for monitoring dental tissue. For example, the condition of dental tissue and deposits over time can be monitored by capturing periodic images showing areas of the orange to red fluorescence. These images can be reviewed and displayed to patients alone or in conjunction with fluorescence-based images of carious regions, in slide-show or animated formats. In one mode of operation, tooth fluorescence emissions obtained with a blue excitation source can be digitally acquired and digitally filtered using an appropriate digital processor to separate the yellow-green (carious detection range) and red-orange (bacterial metabolite detection range) fluorescence images. The original and separated fluorescence images can then be displayed concurrently on an interface to facilitate advising patients of their dental health and of the results of their dental hygiene regimen. 
     It will be understood that in inventive dental implements such as those depicted in  FIGS. 1-7 , the light emitting diode or diodes can be mounted in an alternate location, such as within the handle, and an optical fiber or other suitable light guide can be used to transmit the light to an appropriate location external of the implement for illumination of the oral cavity, for example, a location consistent with the positions of the light emitting diodes shown in  FIGS. 1-7 . These and other similar adaptations of the light source will be apparent to those of ordinary skill in the art from the descriptions herein. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. In addition, all publications cited herein are hereby incorporated be reference in their entirety as if each had been individually incorporated by reference and fully set forth.