Abstract:
A dental instrument, or a coupling connectable to the dental instrument, comprises an illuminator having a plurality of light emitting diodes that are each capable of emitting light at a selected wavelength in a range 260 to 880 nm. White or near white light emitting diodes may also be included together with a switch. Fluorescence-based diagnosis can be assisted by the use of a single dye or mixture of dyes. Light of about 400-540 nm wavelength may be used to distinguish composite, porcelain or other tooth coloured filling materials from normal tooth structures. Light of about 260-450 nm wavelength may be used to identify dental caries, calculus and/or dental plaque. Light of about 350-500 nm wavelength may be used to cure dental composite. Typically, the dental instrument is, or comprises, a drill, de-scaler, or other instruments such as for cleaning, examination or diagnosis of dental conditions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a U.S. National Stage of International Patent Application No. PCT/AU2010/001238, filed Sept. 21, 2010, entitled “Illuminating Dental Instrument, Coupling And Method Of Use,” and which claims the benefit of U.S. Provisional Patent Application No. 61/244,558, filed Sept. 22, 2009, the entire content and disclosure of which are hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     THIS INVENTION relates to dentistry. More particularly, this invention relates to a dental instrument and/or coupling therefor, that provides illumination during drilling, descaling, examination, restoration and other dental procedures. 
     BACKGROUND 
     Much attention has been applied in the recent past to improving the appearance of tooth coloured filling materials, with a wide range of composite resin and porcelain filling materials now available. The aim has been to make these restorative dental filling materials as similar in appearance to tooth structure as possible. The intention is that when a tooth is fractured (traumatically), decayed, severely worn or otherwise damaged, then composite resin and porcelain filling materials with their corresponding adhesives, may be used to restore the tooth to its pre-damaged state. A primary goal has thus been to make the filling “invisible” so that once restored, the tooth appears to be intact, as the restoration is difficult to see visually. 
     As a result, filling materials have evolved to the point whereby they mimic tooth structure in terms of opacity, hue and chromaticity. In the case of some of the higher end composite and porcelain materials available, these restoratives will also provide some fluorescence and opalescence properties as well. At the present time, it is possible to restore a badly broken down tooth with multiple layers of varying coloured composite filling materials, such that it is very difficult to distinguish between natural tooth structure and the prosthetic material. Porcelain restorations manufactured by a skilled dental ceramist can also be very difficult to distinguish from natural tooth structure. 
     However, dental restorations do not last indefinitely, and eventually all composite and porcelain materials begin to wear, break down, leak at their margins or lose their shine and become discoloured. Accordingly, there is a need to remove and/or replace composite and porcelain fillings from teeth. A major concern for the clinician is that the process of removing a filling will result in more tooth structure being ground away and hence more damage occurring to the tooth. With the increasing use of tooth-coloured fillings, which can replicate the optical properties of natural tooth structure, it can be extremely difficult to be certain that no such fillings have escaped recognition or have been misidentified during a clinical examination or when removing an existing filling to access underlying decay. Such fillings are not unambiguously visible. Differences in fluorescence provide such a method for identifying tooth coloured fillings. Tooth-coloured restorative materials, dental caries and calculus have a different fluorescence signature from healthy tooth structure. 
     In the case of modern composite and porcelain filling materials, the overall match in shade between the remaining natural tooth structure and the filling material may be very good, making it difficult to distinguish between restorative material and remaining enamel and dentine. There is the very real risk that excessive tooth structure will be cut or ground away from the natural tooth during removal of an existing filling. The consequence is that the residual tooth will become weaker and may even suffer damage to its pulp (nerve). Additionally, the time it takes a clinician to continuously stop, dry and visualise the remaining tooth-filling interface, increases the length of time needed to perform the procedure and hence the appointments become longer or greatly rushed. There is also the potential problem of not visualising all of the remaining old filling material in the tooth, and hence leaving some behind. This in turn may result in bacteria remaining in the tooth after the new restoration is placed or may compromise bond strengths of the new filling that is subsequently placed, and both of these events may cause further problems post-operatively. 
     Fluorescence can be used in the detection of fillings because the light-induced fluorescence signals from tooth coloured fillings differ from those for normal dental enamel. The fluorescence emission properties of healthy dental enamel were characterized by Angmar-Mansson and others at the Karolinska Institute in the late 1980&#39;s and early 1990s. Visible blue light (470 nm) was shown to elicit yellow fluorescence from the calcium-phosphate bonds in hydroxyapatite. (Sundstrom et al., 1985, Swed Dent J. 9:71-80; Angmar-Mansson et al., 1996, Eur J Oral Sci. 104: 480-485) Previous work on fluorescence identification of tooth coloured fillings has used separate external light sources (Stimpson 1985, Acta Med Leg Soc (Liege) 35:278-284. Pretty et al., 2002, J Forensic Sci. 47:831-6) rather than a diagnostic light which is incorporated into a device for cutting or cleaning, as in the current invention. 
     Another major problem facing the dental clinician relates to caries (decay) in a tooth, either in the form of a new lesion, or recurrent caries beneath a previously placed composite, porcelain or other restoration. Recurrent decay beneath existing fillings poses a particular problem in that any excessive removal of tooth tissue weakens the remaining tooth structure and makes injury to the dental pulp more likely. In order to treat the tooth, the dentist must visualise all of the decay to facilitate its mechanical debridement with a dental handpiece and bur, or with another type of cutting technology, such as a diamond coated tip in an ultrasonic handpiece. The technique that is employed under local anaesthetic is to visualise the discoloured tooth structure, assume it is decay (either by its visualised colour or by tactile feel), and then the tooth is ground with the bur to remove this infected dentine. However, under normal lighting conditions, decayed dentine does not always appear significantly different to the surrounding sound tooth structure, and tactile probing to determine the extent of decay can be very subjective. A very real risk exists that an overly zealous technique may be applied by the dental clinician and that too much tooth structure will be removed in the operative process. This will weaken the tooth and may lead to pulp complications as previously described. Alternatively, and perhaps worse, it is also possible that not all of the decayed tooth structure will be identified by the dentist, and that some decay may be left behind by not removing enough tooth structure before the new filling is placed. A method which can assist the dental clinician in determining that infected dentine still remains will result in more conservative tooth cavity preparations. 
     Tooth decay can proceed at varying rates in different individuals and decay that is deep and rapidly advancing may be difficult to fully detect by normal visual and tactile methods alone. Using dental X-rays can assist in detecting the presence of decay beneath fillings, but this method cannot assist the dental clinician during the procedure, once the filling has been removed and they are then faced with the decision regarding how much natural tooth tissue to remove in the various areas of the cavity. Accordingly, other aides have been used by the clinician to determine the boundary between sound tooth structure and infected diseased structure, so that only the latter is removed. Colour, disclosing dyes, tactile feel, laser light and short wavelength light fluorescence, and resistance to the drill are all techniques that are used. 
     One example, “Carisolv”, is a chemical solution based on sodium hypochlorite with amino acids which attacks that part of the tooth which is decayed. The net result is that demineralised parts of the tooth are softened and a dedicated bur is then used to selectively remove the decayed tooth structure, hopefully without damage to the deeper, sound parts of the tooth. 
     Another approach has been to use a caries (decay) detection dye based on basic fuchsin or acid red dyes. This material is applied to the tooth and will stain caries tissue red and make its appearance distinct from the surrounding tooth. This technique is not particularly specific and may lead to more tooth structure being removed than is necessary. In some instances, red dye will remain in the tooth after the procedure, which may in turn leave a pink hue to the finished filling. 
     The process of fluorescence occurs when incident light applied to a structure is emitted at a longer wavelength, with some conversion of the incident energy into heat. The process of fluorescence has been exploited for a range of diagnostic methods, for example the detection of hidden fissure caries by the DiagnoDENT device, in which visible red laser light (655 nm wavelength) elicits fluorescence in the near infrared region (700-900 nm). Because bacterial products such as porphyrins evoke the fluorescence, the intensity of the emitted light is related to the volume of the carious lesion. Similar fluorescence processes occur with porphyrins in dental calculus, where ultraviolet light elicits red fluorescence, and visible red light elicits near infrared emissions. This process is best termed POSITIVE fluorescence, in that the desired target (in this case the caries or dental calculus) elicits the fluorescence signal. 
     Laser-light based technologies such as the “Diagno-Dent” have been used to measure the near infrared fluorescence signal of bacteria present in the tooth, identifying regions that do not fluoresce strongly in a manner consistent with sound dentine. This device can be used as a diagnostic tool to identify subsurface areas of a tooth where decay is occurring, but cannot be seen from the surface. Following on from this concept, the application of short wavelength light via a dedicated, stand-alone instrument such as the “Sopro Aceon” have also been proposed as a means of illuminating a decayed tooth and stimulating fluorescence of the decayed region. The differential fluorescence between diseased and healthy tooth structure then assists the clinician to distinguish between boundaries in the tooth, allowing more careful removal of only the decayed tooth structure, leaving the sound part of the tooth alone. For light wavelengths from 400 to 420 nm, carious lesions with cavitations in dentine containing bacteria show emissions at 600-700 nm typical for porphyrin compounds (Buchalla, 2005, Caries Res. 39:150-6). The bacteria and their metabolic products induces an increase in the absorption in the UVA and visible blue spectral region from 350-420 nm, which results in the appearance of a fluorescence signal in the visible red spectral region at 590-650 nm (Borisiva et al., 2006, Lasers Med Sci. 21:34-41). 
     Yet another problem that exists pertains to the thorough and complete removal of dental plaque and calculus (tartar) from teeth during a scale and cleaning hygiene appointment. Whilst older, mature calculus that has been on the teeth for a long time may begin to become dark in colour and is readily visible, newer plaque and calculus deposits, as well as the remnants of large deposits that may have been incompletely scaled off the teeth, are often light in colour, frequently matching the shade of the teeth themselves. This can make it very difficult to adequately visualise the bacterial deposits that need to be removed from the teeth. As ultrasonic scaling techniques are performed with a copious water spray, visualisation of the field of cleaning can be compromised, leading to insufficient removal of the plaque and calculus. 
     This problem can be overcome in part by frequently stopping the ultrasonic scaling procedure and thoroughly drying the teeth, in an attempt to observe the remaining plaque and calculus, as this will dry to a “frosty” or “sandy” appearance relative to the shiny natural tooth structure. However, it is often difficult to completely dry the teeth in all parts of the mouth, and this also takes time and draws out the appointment duration. A more ready means of identifying the plaque and calculus on the teeth at the time of debridement would be preferred. 
     As mentioned previously, a disclosing dye may be applied to the teeth prior to scaling and cleaning. The plaque and calculus will then stain pink or red. 
     However, this can lead to excessive staining of the mouth and lips as a whole and is not a technique that is preferred by patients. An alternative approach is to use the concept of fluorescence of bacterial plaque and calculus and hence shining a light of specific wavelength directly onto the teeth to be cleaned. This causes red fluorescence of the bacterial deposits, helping the clinician to identify their location, prior to cleaning. However, this technique requires the frequent and repeated stopping of the scaling process and shining of the light on the teeth in order to have some efficacy. This is an inconvenient process and also contributes to considerable time delays in the scaling and cleaning appointment. 
     The ultraviolet and visible blue wavelengths are desirable for fluorescence diagnosis. Under UVA excitation (363.8 nm), enamel has a fluorescence spectrum which has the shape of a wide band, with a maximum of 450 nm (characteristic of a blue-green shade) and a slow decrease up to 680 nm. The enamel fluorescence does not depend on the colour of the tooth. Dentine has a distribution spectrum which is similar to that of enamel but is three times fuller. The spectra of dental porcelains comprises a wide band due to transition metals, and fine lines due to rare earth elements (terbium and europium). When the saturation degree of the ceramic increases, its fluorescence colour varies due to the relative increase in the amplitude of the lines in relation to the bands. Thus, when the porcelain colour is more saturated, its fluorescence colour becomes greener (Stimpson et al., 1985, supra). 
     With regard to identifying deposits of dental plaque or dental calculus, under UVA and visible blue light, positive red fluorescence from deposits of mature dental plaque on the surface of teeth, restorations, or dental appliances can be identified. This can be done to assist in their controlled removal by a powered scaler, as well as being used as an aid in oral hygiene education. Following tooth cleaning, residual deposits of plaque and calculus appear as red fluorescing areas (Kühnisch et al., 2003, Int Poster J Dent Oral Med 5: 177). Red fluorescence is associated with mature dental plaque on dentures. The maturity of dental plaque, rather than the presence of cariogenic streptococci, is the basis for the red fluorescence (Coulthwaite et al., 2006, Caries Res. 40:112-6). 
     Many of the aforementioned analytical and examination techniques available to dentists, and other techniques, are reviewed in Walsh, 2008, Australasian Dental Practice 19 47. 
     SUMMARY 
     A limitation of prior art dental illuminators such as hereinbefore described is that they are “stand-alone” devices that must be used separately from other dental instruments such as drills, scalers and polishers. This can create practical difficulties for the dentist who has to use two separate devices (i.e illuminator and dental instrument) for examining teeth and performing dental procedures such as removing old tooth coloured filling materials (such as composite resin or porcelain restorations), removing plaque, buffing or polishing teeth and curing dental composite material. 
     The present invention is therefore broadly directed to a dental instrument, or a coupling therefor, comprising an illuminator that is capable of emitting light of a plurality of selectable wavelengths. The illuminator may be in the dental instrument, or may be in a separate coupling operatively connectable to the dental instrument. The wavelength of emitted light may be selected for particular diagnostic purposes and/or for curing dental composite. 
     In one aspect, the invention provides a coupling for a dental instrument, said coupling comprising an illuminator that comprises a plurality of light emitting elements that are each capable of emitting light at a selected wavelength for transmission to said dental instrument. 
     Suitably, the coupling is releasably connectable to the dental instrument. 
     In one embodiment, the coupling comprises a mating portion that is releasably, operatively connectable to a mating portion of the dental instrument. Suitably, according to this embodiment the coupling comprises a plurality of conduits that are releasably connectable to respective conduits in said dental instrument. Said plurality of conduits may comprise one or more water, air, electrical and/or optical conduits connectable to one or more water, air, electrical and/or optical conduits in said dental instrument. 
     In another embodiment, the coupling comprises a fibre-optic conduit releasably mountable to the dental instrument. In use, the fibre-optic conduit emits light transmitted from the coupling. 
     In another aspect, the invention provides a dental instrument operatively connected to the coupling of the aforementioned aspect. 
     In yet another aspect, the invention provides a dental instrument comprising an illuminator that comprises a plurality of light emitting elements that are each capable of emitting light at a selected wavelength. 
     Suitably, in use the illuminator provides sufficient light for the dental instrument to illuminate an oral cavity and/or a dental structure in the oral cavity. 
     In yet another aspect, the invention provides a method of performing a dental procedure on a patient, said method including the step of using a dental a dental instrument according to the aforementioned aspects to perform the dental procedure. 
     In still yet another aspect, the invention provides a method of dental examination of a patient, said method including the step of using a dental instrument according to the aforementioned aspects to perform the dental examination. 
     Preferably, the illuminator further comprises one or more light emitting elements capable of emitting white, or near white, light. 
     Suitably, said plurality of light emitting elements are each capable of emitting light at a selected wavelength in a range 260 to 880 nm. 
     Examples of particular wavelengths within this range include 300 nm, 350 nm, 380 nm, 400 nm, 420 nm, 450 nm, 465 nm, 500 nm, 540 nm, 600 nm, 650 nm, 680 nm, 700 nm, 750 nm and 800 nm and any ranges between any of these wavelengths. 
     Preferably, at least one of said plurality of light emitting elements is capable of emitting light at a selected wavelength in a range selected from the group consisting of: 
     (i) 260 to 450 nm. 
     (ii) 400 to 700 nm; and 
     (iii) 400 to 540 nm. 
     In one particular embodiment, light of about 400 to 540 nm wavelength is used to distinguish composite, porcelain or other tooth coloured filling materials from normal tooth structure such as enamel or dentine. 
     In another particular embodiment, light of about 260 to 450 nm wavelength is used to identify dental caries and/or calculus and dental plaque. 
     In yet another particular embodiment, light of about 350 to 500 nm wavelength is used for curing or photo-polymerizing a dental composite. 
     In a particularly preferred form of the abovementioned aspects, the light emitting elements comprise light-emitting diodes (LEDs). 
     In one particular form, the one or more light emitting elements capable of emitting white, or near white, light may be a white-emitting LED or may be a combination of green, red and blue LEDs. 
     Suitably, the dental instrument and/or coupling further comprises a switch for selecting between said light emitting element capable of emitting white, or near white, light and/or between said light emitting elements that are capable of emitting light at a selected wavelength. 
     In preferred embodiments, the dental instrument is, or comprises, an instrument for inspection, examination, visualization, diagnosis, burnishing, polishing, drilling, scaling, curing or photo-polymerizing dental composite, tooth extraction or other aspects of dentistry. 
     In a particularly preferred embodiment, the dental instrument is a drill or de-scaler. 
     In certain embodiments, fluorescence-based examination, inspection, visualization or diagnosis can be assisted by the use of a single dye or mixture of dyes. Specific dyes can be used which bind selectively to the leaking margins of existing fillings, to areas of early decay in enamel, to areas of decay on root surfaces of teeth, to deposits of plaque of calculus, or to existing types of tooth coloured filling materials. Binding of the dye alters the fluorescence emission and enhances the visual discrimination of these under illumination. 
     In other embodiments, methods utilizing the coupling and/or dental instrument may be facilitated by the use of one or more filters through which the user (e.g. a clinician) examines the illuminated area. These filters suppress or exclude the illuminating wavelength and pass the longer wavelength fluorescence emission so that this can be seen by the clinician. Specific examples include orange and red filters when UVA or visible blue light is produced by the illuminating source. 
     Preferably, the respective wavelengths emitted by the illumination source are matched to one or more long pass optical filters through which a user views an illuminated area. These filters may be attached to the dental instrument may be worn by the user (e.g. in the form of, or attached to protective eyewear or as a mask) or may be handheld as a separate device. 
     The invention is suitable for use in the dental treatment of humans and non-human animals. 
     Throughout this specification, unless the context requires otherwise, the words “comprise”, “comprises” and “comprising” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that preferred embodiments of the present invention may be more readily understood and placed into practical effect, preferred embodiments of the invention will be described, by way of example only, with reference to the accompanying drawing in which: 
         FIGS. 1A  &amp; B shows an embodiment of a dental instrument comprising a compressed air-operated dental drill operatively connectable to a coupling; 
         FIG. 2  shows an embodiment of a dental instrument comprising an electric-powered dental drill operatively connectable to a coupling; 
         FIG. 3  shows an embodiment of a dental instrument comprising a dental de-scaler operatively connectable to a coupling; 
         FIG. 4  shows an embodiment of a coupling and adapter for connecting a fibre-optic conduit to a dental instrument 
         FIG. 5  shows an embodiment of a dental de-scaler having a fibre-optic conduit removably mounted thereto; and 
         FIG. 6  shows an embodiment of a dental instrument comprising an illuminator. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1A and 1B , dental instrument  10  comprises drill  20 , that comprises handle  24  having grip  22 , head  29  comprising drill turbine  27  and drill bit  28  and moveable lens  25 . Coupling  30  includes illuminator  40  that comprises plurality of LEDs  41 . Coupling  30  and dental instrument  20  are releasably, operatively connectable by way of respective mating portions  36  and  26 . For convenience, coupling  30  may be retained in holder  70  which is typically provided on a dental tray (not shown). Referring particularly to  FIG. 1B , coupling  30  is connectable to connector  55  of conduit housing  50  that houses separate compressed air conduit  51  and water conduit  52 , which are respectively connected to sources of compressed air and water (not shown). Coupling  30  comprises air conduit  31  connectable to air conduit  51  and water conduit  32  connectable to water conduit  52 . Coupling  30  further comprises fibre-optic conduit  23  which transmits light emitted by plurality of LEDs  41 . 
     Handle  24  of drill  20  comprises compressed air conduit  21 , water conduit  22  and fibre-optic conduit  23  that respectively connect to compressed air conduit  31 , water conduit  32  and fibre-optic conduit  33  of coupling  30 . In use, compressed air conduit  21  supplies compressed air to drive drill turbine  27  and water conduit  22  supplies water to cool the interface between drill-bit  28  and the dental structure. Moveable lens  25  is positioned in handle  24  proximal to drill-bit  28  to project illumination  80  about the centreline indicated in  FIG. 1B  so that illumination  80  is focussed about or near a patient&#39;s teeth or oral cavity where drilling is performed. 
     In this embodiment, plurality of LEDs  41  in coupling  30  are electrically powered via electrical conduit  54  in connector  55 , which is connected to a source of electrical power (not shown). A switch  37  in the coupling  30  or in a base unit to which it connects allows an LED of an appropriate, specific wavelength, or a white or near white LED, to be selected. 
     It will also be appreciated that coupling  30  could be a “common” coupling  30  comprising compressed air conduit  31 , water conduit  32 , fibre-optic conduit  33  and an electrical conduit (not shown) to enable coupling  30  to be used interchangeably between electrically- and compressed air-powered dental instruments  20 . 
     Accordingly, another embodiment is shown in  FIG. 2 , in which dental instrument  110  is drill  120  that comprises drill bit  128  that is electrically-powered In this embodiment, electrical conduit  1124  in dental instrument  120  connects to electrical conduit  134  of coupling  130  which is connected to electrical conduit  154  of connector  155  and a power source, typically of relatively low voltage such as 6-12V (not shown). In this embodiment, both the drill motor  127  and the LEDs  141  in illuminator  140  are electrically powered. As before, a switch  137  in the coupling  130  or in the base unit to which it connects allows the appropriate LED to be selected. 
     In yet another embodiment shown in  FIG. 3 , dental instrument  210  is de-scaler  220  that comprises handle  224 , having probe  227  with tip  228  and moveable lens  225 . Coupling  230  and dental instrument  220  are releasably connectable by way of respective mating portions  236  and  226 . Referring particularly to  FIG. 3 , coupling  230  is connected to conduit housing  250  which houses separate compressed air conduit  251  and water conduit  252 , which are respectively connected to sources of compressed air and water (not shown). Coupling  230  comprises air conduit  231  connectable to air conduit  251  and water conduit  232  connectable to water conduit  252 . Coupling  230  further comprises fibre-optic conduit  233  which transmits light emitted by plurality of LEDs  241  in illuminator  240  and switch  237 . 
     Another particular embodiment is shown in  FIG. 4 , in which coupling  330  further comprises adapter  360  comprising fibre-optic conduit  361  having light output  362  which is mountable to dental instrument  320  by way of a clip or sleeve (not shown). In this embodiment, fibre-optic conduit  361  transmits light emitted by plurality of LEDs  341  in illuminator  340  located in coupling  330 . 
     In another embodiment shown in  FIG. 5 , dental instrument  410  is ultrasonic de-scaler  420  comprising ultrasonic probe  427  having tip  428 , wherein clip or sleeve  463  is adapted to removably mount fibre-optic conduit  461  from the adapter shown in  FIG. 4 , to ultrasonic scaler  420 . Light output  462  of fibre-optic conduit  461  is positioned in a manner that illuminates teeth (not shown) proximal to tip  428  of ultrasonic probe  427 , thereby providing suitably directed illumination during de-scaling of teeth. 
     In another embodiment in  FIG. 6 , dental instrument  510  is drill  520  that comprises illuminator  540  mounted near head  529 , illuminator  540  comprising plurality of LEDs  541  with moveable lens  525 . Plurality of LEDs  541  receive electrical power from electrical conduit  523  which is connected to an electrical power source (not shown). In this embodiment drill  520  comprises drill bit  528  and air-driven turbine  527  where air conduit  521  is connected to a source of compressed air (not shown). Water conduit  522  is connected to a source of water (not shown) to facilitate cooling turbine  527 . Alternatively, drill  520  may be electrically powered by way of an electrical conduit connected to the electrical power source (not shown). As a further alternative, plurality of LEDs  541  could receive their power by induction generated by the rotation of air-driven turbine  527 . 
     According to the aforementioned embodiments, illuminator  40  would typically comprise plurality of LEDs  41 . LEDs may include one or more UVA, violet, red, green and/or blue LEDs and one or more white or near white LEDs. A switch (not shown) would enable an operator to select violet, red, green, blue or white or near white light, as required. Alternatively, plurality of LEDs  41  comprises one or more UVA, violet, red, green and blue LEDs in the absence of white or near white LEDs. It will be appreciated that in the absence of white or near white LEDs, a switch (not shown) would enable the one or more red, green and blue LEDs to be operated in combination to produce white or near white. 
     In one particular embodiment, the dental instrument  10  or coupling  30  comprises illuminator  40  with plurality of LEDs  41  that include at least one LED capable of producing light at a wavelength suitable for curing or photo-polymerizing a dental composite material. Typically, the at least one LED emits a “blue” wavelength typically in the range 350-500 nm. Dental composites may include photo-initiator molecules to facilitate photo-polymerization of the composite by irradiation with an appropriate wavelength of light. The most common photo-initiator is camphorquinone which absorbs blue light in a wavelength range between about 400 and 500 nm, with peak absorption occurring around 465 nm. Another photo-initiator is phenyl-propanedione (or PPD), which has an ability to absorb light of wavelengths less that 350 nm (near ultra-violet range) to about 470 nm, with its peak absorption occurring at 390 nm. Another even less common photo-initiator used in some dental materials is Lucerin TPO with absorption ability starting below about 350 nm, peaking at about 370 nm and ceasing to absorb light wavelengths above about 420 nm. 
     This particular embodiment enables a dental operator to switch the dental instrument between drilling or scaling modes and a curing or photo-polymerizing mode without the need to change instruments. 
     Use of the coupling  30  and/or dental instrument  10  may be facilitated by the use of one or more filters (not shown) through which the user (e.g. a clinician) examines an illuminated area of the oral cavity. Such filters suppress or exclude the illuminating wavelength and pass the longer wavelength fluorescence emission so that this can be seen by the clinician. Specific examples include orange and red filters when UVA or visible blue light is produced by the illuminating source. 
     These filters may be attached to the dental instrument  10 , may be worn by the user (e.g. in the form of, or attachable to protective eyewear or as a mask) or may be handheld as a separate device such as a “paddle”. 
     The present invention provides a dental instrument having a switchable LED light source in a dental handpiece or coupling, or within the head itself of the handpiece (e.g. a drill or ultrasonic de-scaler), capable of changing between an intense source of illuminating white or near-white light (for standard visualisation and operating) or into a light source of selected wavelengths for visualizing caries, plaque, calculus, tooth coloured fillings and/or natural tooth structure (such as dentine or enamel). 
     The present invention may be installed as a coupling on a dental chair, or alternatively, the fibre-optic coupling of existing dental chair delivery systems would be replaced with the coupling  30  described herein, which would allow the clinician to switch between light outputs as required. Alternatively, the existing light in present couplings could be replaced with a new, switchable LED light source. Either of these embodiments would enable the clinician to keep their existing handpieces and scalers, and continue to plug these into their single, new chair-mounted coupling. 
     In embodiments where the LED illuminator is included in a dental instrument (e.g. a drill or de-scaler without the coupling), such as shown in  FIG. 6 , then the clinician could eventually replace existing dental instruments over time. This would allow the clinician to continue to use existing couplings, and the new handpieces would draw power for the switchable LEDs from the existing coupling systems. 
     In embodiments hereinbefore described with particular reference to  FIGS. 4 and 5 , the illuminator may be a separate, LED light source connected to coupling  330 , and “strapped-on” to an existing handpiece or scaler. The advantage of such an embodiment is that the light source could act in addition to the existing light source in the clinician&#39;s present handpiece or scaler, and would not necessitate the replacement of scalers, handpieces or couplings. 
     Throughout the specification, the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention. 
     All computer programs, algorithms, patent and scientific literature referred to herein is incorporated herein by reference.