WO2010136776A1

WO2010136776A1 - Approximal imaging device

Info

Publication number: WO2010136776A1
Application number: PCT/GB2010/001071
Authority: WO
Inventors: Christopher Longbottom; Emma Perfect; Anne-Marie Haughey
Original assignee: Lux Innovate Limited; The University Court Of The University Of Dundee
Priority date: 2009-05-28
Filing date: 2010-05-28
Publication date: 2010-12-02
Also published as: GB0909206D0

Abstract

The invention relates to an intraoral approximal assessment device comprising an approximal optical portion adapted to fit within an intraoral approximal space, a means of applying a disclosing substance to the intraoral approximal space or at least one of the approximal surfaces of the contacting teeth and a detector, with the the approximal optical portion and the detector being operably connected via a light transmitting material. The invention also relates to a method of assessing one or both of the approximal surfaces of contacting teeth located in the same dental arch and a kit for assessing approximal dental surfaces.

Description

APPROXIMAL IMAGING DEVICE

The invention relates to an intraoral approximal assessment device.

Low light level luminescence or fluorescence detection is useful in a number of areas, such as intraoral diagnoses. In particular, it is useful where a luminescence or fluorescence signal is indicative of a particular condition. However, for some conditions it can be difficult to access the area to be assessed. This may be because of the location on the body or because of pain or discomfort encountered by a patient.

Recently, a method of assessing demineralisation on a tooth surface has been developed, which method uses the free ions released during demineralisation as a biomarker of tooth decay. The detection method uses photoproteins or other light-emitting substances, which emit luminescence or fluorescence in the presence of the free ions. Other methods exist for the detection of plaque, which can also accumulate on approximal tooth surfaces. These methods include the use of indicators that generate detectable signals such as those disclosed in EP 1733762, US 4,302,439 and US 4,992,256. However, there is currently no hardware device that is sufficiently sensitive to detect the light produced using photoproteins or other light emitting substances, especially from the approximal regions.

Many devices have been designed for the purpose of intra-oral imaging. These prior art devices tend to be relatively insensitive to low levels of light, particularly in the presence of ambient light. The devices often have a pen-like shape, which is held in the intraoral cavity by the operator. Such devices cannot be used for detecting low levels of luminescence or fluorescence emitted from surfaces exposed to ambient light. It is particularly difficult to capture light that is emitted from the area of the embrasure in the region where teeth are in contact; in other words, for assessment of caries or plaque that form on approximal dental surfaces or in the intraoral approximal space.

Approximal, also known as proximal or inter-proximal, caries lesions form on the smooth contacting surfaces of adjacent teeth and usually just under the contact areas of the two teeth. Due to this location, which is not readily accessible, they are difficult to detect. Direct visualization or physical detection with a probe is used for detection of caries lesions on other surfaces but does not work readily for approximal lesions. Separators, also known as spacers, may be placed between teeth prior to assessment in order to facilitate visual access. However, this requires an extra visit and patients may refuse to accept them due to discomfort or for aesthetic reasons. In addition, there may be impaction of food into the space created after the use of separators. Even where separators are used the clinical assessment of the surface is subjective and may not be accurate.

Radiographs are usually used for detection of approximal caries, although comparison work to histological 'gold standards' suggest it is not quite so sensitive in the context of detection of incipient proximal caries lesions (Moreira da Silva Neto et al 2008, Braz. Dent. J. vol.19 no.2), that is, those lesions at the enamel-only stage. Some other detection technologies are suggested for the detection of approximal caries lesions. For example, DEFOTI (Digital Imaging Fiber-Optic Trans-Illumination), which does not require placement into the intraoral approximal space. Also, a fluorescence device that uses a fluorescence dye, which is taken up by the caries lesion, and bifurcating glass fibre bundle, one for excitation and one for emission have been used in vitro (Van de Rijke J. W. and Ten Bosch J. J. 1990, Optical Quantification of Caries-like Lesions in vitro by Use of a Fluorescent Dye, Journal of Dental Research; 69; 1184). Other devices such as DIAGNOdent include a pen-like device, one version of which uses a probe with a tip that fits into the embrasure of contacting teeth. These known devices do not fit easily into the intraoral approximal space for the detection and assessment of approximal caries (Haak et al, Abstract 73 Accessibility of Approximal Tooth Surfaces with a Laser Fluorescence Pen Device in vivo Caries 294 Res 2007;41 :268-334). Additionally, currently available devices do not separately detect light from approximal surfaces of two adjacent and contacting teeth, during a single assessment. In contexts unrelated to detection of lesions, light-transmitting approximal wedges and light sources are available to cure resins. However, these cannot be used for detection since light is emitted as opposed to detected. They also do not differentiate between the approximal surfaces of adjacent teeth, with light being transmitted to both surfaces. It is an object of the invention to provide a device which seeks to mitigate some or all of the above-described problems.

In a first aspect of the invention, there is provided an intraoral approximal assessment device, wherein an intraoral approximal space is formed between contacting teeth with approximal surfaces of the contacting teeth located on opposite sides of the intraoral approximal space, the contacting teeth being located in the same dental arch; said device comprising; a. an approximal optical portion adapted to fit within the intraoral approximal space; b. a means of applying a disclosing substance to the intraoral approximal space or at least one of the approximal surfaces of the contacting teeth; and c. a detector; the approximal optical portion and the detector being operably connected via a light transmitting material.

The phrase "same dental arch" refers to a single dental arch, i.e. either the upper arch of teeth within a person's mouth or the lower arch of teeth within a person's mouth.

This device allows the user to detect light emitted from an approximal surface and specifically allows low levels of luminescence or fluorescence to be detected from one or both of the surfaces of two adjacent and contacting teeth, or from the intraoral approximal space. The user will therefore conveniently be able to assess the quantity of light emitted from a tooth surface and detect caries or plaque that may be forming on the approximal surfaces. Once a caries lesion or plaque has been identified, treatment decisions on subsequent preventive or operative care can be made. By including the applicator means within the imaging device, it is ensured that the light emitted on application of the disclosing substance can be captured as quickly as possible following the contact between the tooth surface and the disclosing solution. The space available between approximal surfaces is limited and a single device which enables the detection of luminescence or fluorescence from one or both of the surfaces has advantages for patient comfort. When the disclosing substance requires excitation, then an excitation energy source may be positioned out with the intraoral approximal space, for example from an occlusal surface and transmitted through the tooth surface to the intraoral approximal space. The excitation energy source may comprise a UV lamp, LED or laser.

Preferably, a handle is attached to the portion of the device adjacent the detector. This will enable the user to manoeuvre the device into the intraoral approximal space in a simple and hygienic manner.

Preferably, wherein the approximal optical portion comprises two parts and the two approximal optical parts may be placed together in the intraoral approximal space so that an outside surface of each part faces one of each of the two approximal surfaces of the contacting teeth. Thus, the user is able to detect light and assess the surfaces of two adjacent contacting teeth with one procedure, which is beneficial to the patient and the operator in terms of speed of assessment and the cost of the disposable portion, where the approximal portion is to be disposable.

Preferably, a reflective material is present within the join between the two parts. The reflective material will ensure that, where light from two adjacent teeth is being detected, the light from either tooth will not be mixed and therefore the user will be able to distinguish between light emitted from one tooth and light emitted from the other tooth. The reflective material may be bonded to or may coat the surfaces of the two parts which are adjacent one another when the two parts are placed together to form the approximal portion.

Preferably, at least one optical fibre is connected to each of the two parts. This will help to ensure that any light detected by one part is kept separate from the light from the second part, so that the user is able to distinguish between the light emitted from different surfaces.

Preferably, the approximal optical portion is disposable. As such, it will not be necessary to sterilise the device after each use; instead, the approximal optical portion can simply be discarded. This device will therefore be simple and quick to use in a clinical setting. Furthermore, manufacturing will be made simpler, as the manufacturer will not be limited to specific materials, for example those that may be autoclaved. Preferably, the light transmitting material is one of at least one optical fibre, at least one solid glass rod, or a collimator. Preferably, the light transmitting material is provided with a coating, the coating having light absorbing or reflecting properties to prevent ambient light entering the device. Thus, when the device is being used in the clinic, ambient light will interfere to a reduced extent with the light signal from the tooth and the signal to background ratio will be improved.

Preferably, the detector is one of a charge coupled device (CCD), complementary metal-oxide semiconductor (CMOS), charged injection device (CED), digital camera, intensified camera, videoscope, at least one light sensitive material such as photographic film or light sensitive putty, photometric detector, photomultiplier tubes (PMT), micro-electro-mechanical system (MEMS), photodiode, amplified photodiode (APD), light sensitive semiconductor or a combination of these. Where a number of different detectors are used, they may be arranged as an array. For, example, an array of PMTs could be used to increase sensitivity or a CCD and PMT in combination could provide the option of either detecting total light or capturing an image.

The signal from the detector may be converted to a user friendly output. This may be a number, an image, a sound, a graph, a vibration or a combination of these. Suitable output display means include oscilloscopes, a digital display (including liquid crystal displays (LCD)), light emitting diodes (LED), vector displays, flat panel displays, vacuum fluorescent (VF) displays, electroluminescent displays (ELD), plasma display panels (PDP), high performance addressing (HPA) displays, thin-film transistor (TFT) displays, organic light- emitting diode (OLED) displays, surface-conduction electron-emitter displays (SED) and laser displays. Software may be used to produce a display on a monitor or on the device itself, whilst a loudspeaker or electrical signal generator may be used to generate an audible output.

The means for applying a disclosing substance may have one or more outlets located in the portion of the device that fits in the intraoral approximal space for accurate transfer of the disclosing substance to the proximal surface. The means for applying a disclosing substance may be an injector device. Alternatively, the means for applying a disclosing substance may be a spray gun. This will enable the user to control the exposure of the tooth surface to the disclosing substance; as much or as little tooth surface will be exposed, depending on the width of the jet or spray.

Preferably, the approximal optical portion is coated or impregnated with a disclosing substance. This ensures that as soon as the approximal optical portion is placed in the intraoral

approximal space, the disclosing substance will come into contact with the approximal surface or intraoral approximal space. If any of the target substance is present, for example free ions that have been released due to demineralisation, then a signal will be emitted by the disclosing substance indicating the presence of caries. By impregnating or coating the approximal optical portion itself, the device is simplified because there is no requirement for a separate injector device to be incorporated into the imaging device. In addition, the luminescent or fluorescent signal could be detected as soon as it is created. A means of controlling the release or activation of the disclosing substance may be included. For example, the substance that coats or impregnates the approximal optical portion may be dissolved through addition of a second solution, a method of heating the disclosing substance may cause it to melt and be released, or light of a particular wavelength may be transmitted to the approximal optical portion to cause a chemical change in the disclosing substance and release or activate the disclosing substance.

Preferably, the device includes means for reducing the ambient light that may be detected by the device. The means for reducing ambient light may include a skirt that may surround the approximal optical portion to shield and/or cover the teeth being assessed. The mouth is not easy for a dentist to work within, particularly if the signal to be detected is a luminescent or fluorescent one, because of the interference from ambient light and the low levels of luminescence or fluorescence expected. However, by providing a skirt around the device and the tooth or teeth, ambient light is reduced so that the user can be sure that he is detecting light that has been produced due to contact between the tooth and the disclosing substance.

Preferably, the means for reducing ambient light includes a mouth shield, which would be positioned externally, near to the lips. Such shields effectively block the entry of ambient light into the mouth, improving the signal to background ratio achievable with the device. Mouth shields may be used as well as or instead of a skirt. Preferably, the approximal optical portion is manufactured from an extremely low friction material. By 'low friction' it is meant that the portion slides easily across dental surfaces, creating little friction against them. As such, it will be easier for the portion to be inserted into the tight space between adjacent teeth. Such materials may include Teflon and parylene.

hi a second embodiment of the invention, a method of assessing one or both approximal surfaces of contacting teeth located in the same dental arch using the device as hereinabove described is provided. The method comprises the steps of placing the approximal optical portion in an intraoral approximal space, applying a disclosing substance to the intraoral approximal space or at least one of the approximal surfaces and detecting light emitted from one or both of the approximal surfaces. The user will therefore conveniently be able to assess the quantity of light emitted from a tooth surface and detect caries or plaque that may be forming on the approximal surfaces. As the device is placed directly into the embrasure of contacting teeth, it is possible for the user to detect precisely from where the light is being emitted. Furthermore, the user is able to simultaneously but separately detect light coming from two adjacent surfaces rather than from only one at a time. Once a caries lesion or plaque has been identified, treatment decisions on subsequent preventive or operative care can be made.

Preferably, the method further comprises the step of inserting a temporary separator, also known as a spacer, in between the teeth prior to placing the approximal optical portion in an intraoral approximal space to aid insertion of the approximal optical portion. The temporary separator may be placed in between the teeth in the days prior to the assessment. The clinical practitioner would be able to assess how long is required in order to separate the teeth sufficiently.

Preferably, the method further comprises the step of applying the disclosing substance to the intraoral approximal space or at least one of the approximal surfaces prior to or simultaneously with inserting the approximal optical portion. The assessment device may be used to apply the disclosing substance. Using the same device to apply the disclosing substance and detect the emitted luminescent or fluorescent signal avoids the need for a second device, optimises the speed of the process and the cost of the device. This would be particularly useful, for example, if the disclosing substance is lubricating, as it would assist the placing of the approximal optical portion in between the teeth. If the disclosing substance is a slow-release formulation in which the luminescence or fluorescence signal is emitted over an extended period of time, e.g. several seconds up to several minutes, or if release of the disclosing substance can be controlled in the time domain, there would then be sufficient time to place the optical portion correctly and also detect any emitted signal.

Alternatively, the method further comprises the step of applying a disclosing solution to the approximal surface after insertion of the approximal optical portion. If the disclosing solution is applied after insertion of the device, then the device is already in position to ensure that all light emitted due to contact between the dental tissue and the disclosing substance will be captured by the detector.

Preferably, the disclosing substance may be released or activated by a method selected from; light exposure, heat or contact with saliva or another activating solution. This step will be performed either on the approximal portion, where the disclosing substance is impregnated in the approximal portion, or on the intraoral surface to which the disclosing substance has been applied.

Preferably, where the surfaces are to be investigated for caries lesions they are appropriately prepared prior to placing the approximal optical portion in an intraoral approximal space by removal of plaque, for example they may be flossed and/or brushed interdentally, prior to the insertion of the approximal device and application of the disclosing substance to optimise the signal-to-noise ratio.

Preferably, the method will further comprise the step of comparing the level of light emitted by at least one of the approximal surfaces with the level of light emitted by control surfaces. These control surfaces may be provided in a kit along with the device or may be approximal surfaces which are not considered to have caries or plaque. The control surfaces would indicate the light that should be generated from an intact or non-carious dental surface, but may be constructed from materials with slightly different properties, ideally specific to the patient. This would aid with diagnosis by accounting for variability within and between individuals as well as any variability in the disclosing substance used.

Preferably, the method will further comprise the step of comparing the level of light emitted by at least one of the approximal surfaces with the level of light emitted by a control material. The control materials may contain a pre-determined concentration of free, or available, ions - preferably calcium ions - so that the level of light emitted from the tooth surface can be compared with the level of light emitted from the control material to quantify the amount of free ions present on the dental surface. This would aid with quantification as well as aid diagnosis. Control material may be salts dried or in solution and which may be coated onto a solid surface or may be hydroxyapatite discs.

The operator may compare the level of light emitted with a pre-determined threshold. For example, a certain amount of emitted light may indicate that dental treatment intervention is required.

In a third embodiment of the invention, there is provided a kit for assessing approximal dental surfaces comprising the device as hereinabove described and a disclosing substance.

Preferably, the disclosing substance generates an optical signal in the presence of plaque, low pH, bacterial metabolites, or mineral release from surface during the process of demineralization caused by bacterial acid attack. These are important 'indicators' for dental disease. The plaque enables caries to form, lactic acid causes lowering of pH and demineralization of dental hard tissue, and the products of demineralization provide an indication of the presence of active caries lesions or, if assessment follows an acid wash, sensitization or erosion susceptibility.

The disclosing substance may contain at least one luminescent material. Suitable luminescent materials may be selected from the list consisting of aqueorin, obelin, clytin, mitrocomin, halistaurin, phialidin, mnemiopsin, symplectin, gr-bolinopsin and berovin. These materials are photoproteins that luminesce in the presence of calcium, one of the products of demineralization. Preferably, the at least one luminescent material is aqueorin or obelin. The disclosing substance may contain at least one fluorescent material. Suitable fluorescent materials may be selected from the list consisting of fluorescein, ion sensitive markers such as cameleon indicators, Pericam, Camgaroo Fura-2, Calcium Green- 1, Fluo-3, Indo-1, Rhod-2 and cSNARF-1 Quin 2, Mag-indo 1, Mag-fura 2 (furaptra), Mag-fura 5, Indo IFF, Fura 2FF, Indo PE3, Fura PE3, Bis-fura 2, Ci₈-fura 2, FIPl 8, FFPl 8, Benzothiaza-1, Benzothiaza-2, Fluo-LR, Fluo 4, Fluo 5N, Mag-fluo 4, Calcium green-2, Calcium green- 5N, Calcium orange, Calcium orange-5N, Calcium crimson, Oregon green BAPTA 488-1 , Oregon green BAPTA 488-2, Oregon green BAPTA 488-5N, Fura red, X-rhod 1, Rhod 5N, X-rhod 5N, Mag-rhod 2, Mag-X-rhod 1, Calcium green C₁₈, Fura-indoline-Ci₈ for calcium; Mag-Fura-2 and Mag- Fura-3 for magnesium; Zr(FV)-EDTA-oxine, boronic acid compounds, thioureido naphthalene derivatives and coumarin derivatives for fluoride; sodium-binding benzofuran isophthalate for potassium; and OsteoSense for hydroxyapatite. However, any other molecular structure that can be labeled with fluorophores and used to detect calcium or other products of demineralization through detection of fluorescence, quenching of fluorescence or through a conformation change may be suitable for use in the present invention. Where the disclosing substance comprises at least one fluorescent material, an excitation source may be included in the kit. The excitation source may comprise at least one of an LED, a lamp and a laser.

Preferably, the kit further includes a set of control surfaces and/or a set of control materials. This would aid with diagnosis by accounting for variability within and between individuals as well as any variability in the disclosing substance used.

The invention will now be described with reference to the following Experiments and Figures, in which:

Figure 1 shows the signal obtained from Glowell® calibration units and demineralised tooth surfaces following application of Glowdent™ and as determined with optical fibre and PMT setup.

Figure 2 shows the signal obtained from different quantities of calcium ions following application of Glowdent™ and as determined with optical fibre and PMT setup. Figure 3 shows the signal obtained from freshly extracted teeth with caries lesions following application of Glowdent™ and as determined with optical fibre -PMT device.

Figure 4 shows the signal obtained from optical fϊbre-PMT device with and without approximal optical portion.

Figure 5 shows the signal obtained from optical fibre-PMT device using an approximal optical portion incorporating either reflective or white material.

Figure 6 shows an embodiment of the device according to the invention wherein the device is placed into the embrasure of contacting molars in the lower dental arch and is shown from an orthogonal projection from the position of a horizontal view through the object. Hatching indicates the light transmitting material, grey indicates reflective material of approximal optical portion and black indicates the detector.

Figure 7 shows an embodiment of the device according to the invention wherein the device is placed into the embrasure of contacting molars in the lower dental arch and is shown from an oblique projection. Hatching indicates the light transmitting material and grey indicates reflective material of approximal optical portion.

Figure 8 shows an embodiment of the approximal optical portion as viewed from different angles. Hatching indicates the light transmitting material, grey indicates reflective material of approximal optical portion, no colour indicates the light transmitting material of the approximal optical portion and dotted area indicates the contact point.

Figure 9 shows, from an orthogonal projection from the position of a horizontal view through the object, an approximal optical portion comprising two parts and how the two approximal optical parts may be positioned together within the embrasure of contacting teeth and so used to collect light from each opposing surfaces at the same time. Hatching indicates the light transmitting material, grey indicates reflective material of approximal optical portion and no colour indicates the light transmitting material of the approximal optical portion. Experiment 1 : Demonstration of optical fibre-PMT device to assess active caries lesions using demineralised teeth

Figure 1 shows the signal obtained from blue G3 and G2 Glowell® 96-well plate calibration units, which provide a constant light output, and teeth (demineralised and not demineralised). Teeth were demineralised using a standard method, by immersion in 1% citric acid for 3 minutes and then rinsing with deionised water. All readings were conducted in a dark box using an optical fibre-PMT assembly and the optical fibre tip was placed on the Glowell® or demineralised tooth surface which were held in a plastic holder. Two 100s (gate time - Is) readings were taken for each Glowell®. When capturing data from teeth an image was taken before and after application of 250 μL Glowdent™, a chemical which binds to calcium ions generating blue light. Results show that the optical fibre and PMT set up is suitable for transferring light and detecting the light signal emitted from tooth surfaces.

Experiment 2: Demonstration of optical fibre-PMT device to assess different quantities of calcium ions

Figure 2 shows the signal obtained following injection of 200 μL Glowdent™ to wells of a 96 well plate containing 10 μL of calcium acetate solutions of differing concentrations. All readings were conducted in a dark box using an optical fibre-PMT assembly and the optical fibre tip was placed at 90 degrees to surface, just above the well. Two 100s (gate time - Is) readings were taken and experiment performed in duplicate. Results show that the optical fibre-PMT set up may be used to quantify calcium present in a sample.

Experiment 3: Demonstration of optical fibre-PMT device using freshly extracted teeth

Figure 3 shows the signal obtained from two freshly extracted deciduous teeth, extracted due to active caries. Experiments were performed in a dark box using an optical fibre-PMT assembly and each tooth was rinsed after extraction. Unlike experiment 1, the PMT was switched on before 250 μL Glowdent™ was injected onto the tooth and signal over 100s (gate time of 1 s) determined. Different responses were observed from different teeth. Experiment 4. Signal obtained from optical fibre-PMT device with and without approximal optical portion

Figure 4 shows signal obtained from different apertures of white LLIS Glowell® calibration standard (1 s read, performed in duplicate in a dark box), where GO is designed to emit more light than G2 which emits more light that G3. Incorporation of an approximal optical portion into the device reduces transmission efficiency although the relative amounts of light transmitted is the same with or without the wedge.

Experiment 5. Signal obtained from optical fibre-PMT using approximal optical portions containing different materials

Figure 5 shows the signal obtained from the G2 aperture of a white LLIS Glowell® calibration standard (1 s read, performed in duplicate, in a dark box), using the setup shown. The amount of light transmitted through the approximal optical portion was dependent on the material used (at position A). Thus, when a reflective foil material was used more light was transmitted than when a white material was used. The inclusion of a reflective material may help enhance low light signals.

In the embodiment shown in Figures 6 to 9, the approximal optical portion (the portion of the device which is placed in between the two adjacent teeth) is comprised of two triangular- shaped parts, which together are shaped and sized to fit within the embrasure of contacting teeth. Therefore, the device can detect light separately from two approximal surfaces of adjacent and contacting teeth during one assessment. The two parts may be joined and inserted into the intraoral approximal space together or separately. The two parts are joined so that the outside surface of each portion faces one of the approximal surfaces of the adjacent teeth and the join extends along a direction running at right angles to the line of the arch of the teeth through the intraoral approximal space. The shape of each of the two parts together may be a tapered wedge, square or rectangular in cross section, triangular in vertical section (along the line of the dental arch), so that the two parts fit together with the base (that is the horizontally aligned side facing: a) downwards in the lower dental arch and b) upwards in the upper dental arch) of each wedge towards the bone supporting the teeth. Viewed from above, as illustrated in Figure 8, the individual parts are shaped substantially as a right-angled triangle, with a long straight edge and a short straight edge emerging at right angles to each other. The third edge may be straight or curved, or shaped to conform with the tooth against which it will sit. Preferably the wedge tapers to a curved rather than sharp point for patient comfort, although the point will be narrow and sufficiently stiff to allow it to be easily inserted. Fibres may be attached to the tapered end so that the wedge can be 'pulled through' the gap in the teeth. Wedges to capture light from opposing surfaces of adjacent teeth may fit together, so that the long straight edges are in contact, the short straight edges are opposing and the third edges face towards the cusps of the tooth. The wedges will therefore cover the full length of the approximal surface and lie below the contact point where plaque is most likely to accumulate and caries lesions most likely to form. The two wedges will preferably be inserted into the intraoral approximal space sequentially, unless a separator has been used. Thus, the thinnest part of the approximal optical portion will be located, when the device is inserted, in the central part of the area between the two teeth, this area normally being occupied by gum tissue, which can be readily displaced slightly by the optical portion. This is particularly useful because there can be significant contact-pressure between two teeth; thus it is desirable that the approximal optical portion of the device be as slim as possible to permit insertion into the intraoral approximal space. The approximal optical portion serves to collect light that is being emitted from the tooth surfaces.

A reflective material is present, in this embodiment of the invention, within the join between the two parts of the approximal optical portion. That is, the reflective material is across the surface of each part that is furthest away from the approximal surface. Thus, the light that is emitted from one approximal tooth surface will be collected from one part, and the light that is emitted from the contacting surface of the approximating tooth is collected from the other part simultaneously. The reflective material ensures that the light from the different surfaces will not be mixed, so that the device can be used therefore to determine the presence of, for example, active caries on either approximal surface.

An optical fibre is attached to the short straight non-tapered edge of each part of the approximal optical portion. The optical fibre transmits the collected light from the approximal optical portion to the detector. The fibres may be flexible, which enables the best fit into the intraoral space, and the least amount of discomfort to the patient. However, the optical fibres may also be rigid if it is necessary to use a rigid material because of its particular optical properties. Alternatively, the light may travel through a collimator towards the detector. There may be a glass rod or fibreoptic bundle between the approximal optical portion and the detector through which light passes. Preferably the fibres between the approximal optical portion and detector are coated with a material that does not allow entry of ambient light into the fibres. A reflective material or a material that absorbs light may be used.

A handle may also be attached to the short straight edge of each part of the approximal optical portion. This handle is positioned so that the user can push the end of the device into position in between the two teeth to be assessed. Alternatively, as mentioned previously, a fibre, thread or dental-floss-like material could be attached to the tapered end to 'pull' the approximal optical portion into place.

The device may include, according to the invention, an applicator for applying the disclosing substance. The applicator is positioned such that it does not interfere with placement of the approximal optical portion, and so that the disclosing substance can be released onto the surface to be assessed. This applicator may be an injector, incorporated in the device so that when a button or trigger is pressed a disclosing substance is transferred onto the surface to be assessed. (The detection system may be activated simultaneously by the same button or trigger.) Alternatively, the device may be designed according to the invention so that on placement on a surface a disclosing substance, e.g. for detection of active caries or plaque, is released through pressure, heating or contact with saliva. The disclosing substance may be a gel, a solution or a solid.

The device may be manufactured by injection moulding, casting, blow moulding, bulk moulding, compression moulding, extrusion, rotational moulding, transfer moulding or thermoforming. The approximal optical portion should, as it will be placed within the mouth, be manufactured of a non-toxic substance. In addition, it would be ideal if it were to be manufactured from or coated with a low-friction material such as Teflon, HDPE, PTFE, nylon or ultra-hard carbon films, MoS2 or diamond films, to enhance the ease of insertion of the approximal optical portion into place. However, the detector may be manufactured of any material suitable for sterilisation. Polystyrene, polyacrylic or polypropylene are particularly suitable for this purpose. In some embodiments of the invention, there is a "skirt" around the device. The skirt is designed to reduce ambient light at the detector site and may help protect the device from saliva or other fluids. The skirt may be made from an opaque material or a material, such as a band pass filter, that only allows light of certain wavelengths to be transmitted.

The device is used with a disclosing substance that generates an optical signal in the presence of plaque, low pH, bacterial metabolites, or mineral release from surface during the process of demineralization caused by bacterial acid attack. Preferably the disclosing substance is a luminescent or fluorescent material, which generates an optical signal in the presence of calcium ions. Calcium is a key ion present in teeth and is released on demineralization of enamel and dentine as occurs in active caries lesions and erosion or following application of an acid or sugar solution to the tooth surface.

In some embodiments, means for reducing ambient light may include a mouth shield used with or added to the device to prevent ambient light from the room from entering a patient's mouth. This shield may be opaque to block out all light, or coloured to block out light of a particular wavelength. This may help reduce background noise and improve the quality of the signal. For example, the filter may only allow light corresponding to that of the luminescence or fluorescent material to pass through to the chip. A coloured shield may allow a dental practitioner or doctor to look into the mouth but block light of interfering wavelengths from entering the mouth.

A band pass filter could be used to block out any wavelengths of light that are not attributable to the luminescence or fluorescence signal of interest. When aequorin or obelin are being used for detection of free ions on an intraoral surface, bandpass filters that transmit light efficiently at 465 or 485 nm respectively could be used. These would be positioned upstream along the path of light transmission, so that the light would be filtered before reaching the detection device in the imaging portion. In addition, a CCD, CMOS, CID, digital camera, intensified camera, videoscope, light sensitive materials such as photographic film or light sensitive putty, photometric detector, photomultiplier, MEMS, PMT, photodiode, APD, light sensitive semiconductor or a combination of these may be used for detection that is sensitive to particular wavelengths of light. In embodiments in which a luminescent signal is to be detected from either aqueorin or obelin, a CCD or other detector which is sensitive to blue light of 465 or 485 nm respectively could be used to detect light in a luminescent assay, and a red or green sensitive CCD, or other detector could be used to obtain a visible image of the tooth surface.

The device may be operably attached to a computer. The advantages of this are numerous. The user would be able, using software programs installed on the computer, to manipulate or analyse the data, and save data produced by the device. Preferably, the device is connected to the computer via wireless means. This would ensure that the user would not be concerned with wires trailing around the lab or surgery, which could be inconvenient or a trip hazard. Furthermore, it can be difficult to produce a clear image or a distinct measurement of a weak luminescence or fluorescence signal, especially if a camera is moving. If wires were attached to the device, this could cause the device to be 'dragged' due to the weight of the wires, preventing the camera from remaining still.

One embodiment of the device may further, according to the invention, include a mouth shield. The shield could be placed around the mouth and the device, in order to further exclude any ambient light from coming into the area to be assessed.

One embodiment of the kit include a mirror. The mirror would be useful where the device is to be used for intra-oral use, because the dental practitioner would be able to locate the correct area and position the assessment device correctly in the mouth before applying the disclosing solution. The mirror could also be used to check that the disclosing solution had covered the approximal surface(s) being assessed.

Claims

CLAIMS:

1. An intraoral approximal assessment device, wherein an intraoral approximal space is formed between contacting teeth with approximal surfaces of the contacting teeth located on opposite sides of the intraoral approximal space, the contacting teeth being located in the same dental arch; said device comprising; a. an approximal optical portion adapted to fit within the intraoral approximal space; b. a means of applying a disclosing substance to the intraoral approximal space or at least one of the approximal surfaces of the contacting teeth; and c. a detector; the approximal optical portion and the detector being operably connected via a light transmitting material.

2. A device according to claim 1 , wherein a handle is attached to the portion of the device adjacent the detector.

3. A device according to claim 1 or claim 2, wherein the approximal optical portion comprises two parts and the two approximal optical parts may be placed together in the intraoral approximal space so that an outside surface of each part faces one of each of the two approximal surfaces of the contacting teeth.

4. A device according to claim 3, wherein a reflective material is present within the join between the two parts.

5. A device according to any preceding claim, wherein at least one optical fibre is connected to each of the two parts.

6. A device according to any preceding claim, wherein the approximal optical portion is disposable.

7. A device according to any preceding claim, wherein the light transmitting material is one of at least one optical fibre, at least one solid glass rod, or a collimator.

8. A device according to claim 7, wherein the light transmitting material is provided with a coating, the coating having light absorbing or reflecting properties to prevent ambient light entering the device.

9. A device according to any preceding claim, wherein the detector is one of a charge coupled device (CCD), complementary metal-oxide semiconductor (CMOS), charged injection device (CID), digital camera, intensified camera, videoscope, at least one light sensitive material such as photographic film or light sensitive putty, photometric detector, photomultiplier tubes (PMTs), micro-electro-mechanical system (MEMS), photodiode, amplified photodiode (APD), light sensitive semiconductor or a combination of these.

10. A device according to any preceding claim, further including means to convert a signal from the detector into a user-friendly output selected from one of a number, an image, a sound, a graph, a vibration or a combination of these.

11. A device according to any preceding claim, further including at least one of an oscilloscope, a digital display such as a liquid crystal display (LCD), a light emitting diodes (LED), a vector display, a flat panel display, a vacuum fluorescent (VF) display, an electroluminescent display (ELD), a plasma display panel (PDP), a high performance addressing (HPA) display, a thin-film transistor (TFT) display, an organic light-emitting diode (OLED) display, a surface-conduction electron-emitter display (SED), a laser display, software to produce a display on a monitor or on the device itself, a loudspeaker or an electrical signal generator.

12. A device according to any preceding claim, wherein the means for applying a disclosing substance has one or more outlets located in the portion of the device that fits in the intraoral approximal space.

13. A device according to any preceding claim, wherein the means for applying a disclosing substance is an injector device.

14. A device according to any of claims 1 to 12, wherein the means for applying a disclosing substance is a spray gun.

15. A device according to any preceding claim, wherein the approximal optical portion is coated or impregnated with a disclosing substance.

16. A device according to any preceding claim, further including means for reducing the ambient light that may be detected by the device.

17. A device according to claim 16, wherein the means for reducing the ambient light includes a skirt that shields and/or covers the teeth being assessed.

18. A device according to claim 16 or 17, wherein the means for reducing the ambient light includes a mouth shield.

19. A device according to any preceding claim, wherein the approximal optical portion is manufactured from an extremely low friction material.

20. A method of assessing one or both of the approximal surfaces of contacting teeth located in the same dental arch using the device of any preceding claim, the method comprising the steps of: a. placing the approximal optical portion in an intraoral approximal space, b. applying a disclosing substance to the intraoral approximal space or at least one of the approximal surfaces, and c. detecting light emitted from one or both of the approximal surfaces.

21. A method according to claim 20, further comprising the step of inserting a temporary separator in between the teeth prior to placing the approximal optical portion in an intraoral approximal space to aid insertion of the approximal optical portion.

22. A method according to claim 20 or 21, wherein the disclosing substance is applied to the intraoral approximal space or at least one of the approximal surfaces prior to inserting the approximal optical portion.

23. A method according to claim 20 or 21, wherein the disclosing substance is applied to the intraoral approximal space or at least one of the approximal surfaces simultaneously with insertion of the approximal optical portion.

24. A method according to claim 20 or 21, wherein applying the disclosing substance to one or both approximal surfaces occurs after insertion of the approximal optical portion.

25. A method according to any of claims 17 to 24, wherein the disclosing substance is released or activated by a method selected from; light exposure, heat or contact with saliva or another activating solution.

26. A method according to any of claims 17 to 25 further including the step of removal of plaque prior to placing the approximal optical portion in an intraoral approximal space.

27. A method according to any of claims 17 to 26 further comprising the step of comparing the level of light emitted by at least one of the approximal surfaces with the level of light emitted by control surfaces.

28. A method according to any of claims 17 to 27 further comprising the step of comparing the level of light emitted by at least one of the approximal surfaces with the level of light emitted by a control material.

29. A method according to any of claims 17 to 28 wherein the level of light emitted is compared with a pre-determined threshold.

30. A kit for assessing approximal dental surfaces comprising the device as described in any of claims 1-19 and a disclosing substance.

31. A kit according to claim 30, wherein the disclosing substance generates an optical signal in the presence of plaque, low pH, bacterial metabolites, or mineral release from surface during the process of demineralization caused by bacterial acid attack.

32. A kit according to claim 30 or 31, wherein the disclosing substance contains at least one luminescent material.

33. A kit according to claim 32, wherein the disclosing substance is selected from the list consisting of aequorin, obelin, clytin, mitrocomin, halistaurin, phialidin, mnemiopsin, symplectin, gr-bolinopsin and berovin.

34. A kit according to any of claims 30 to 33, wherein the disclosing substance contains at least one fluorescent material.

35. A kit according to claim 34, wherein the disclosing substance is selected from the list consisting of fluorescein, ion sensitive markers such as cameleon indicators, Pericam, Camgaroo Fura-2, Calcium Green- 1, Fluo-3, Indo-l,,Rhod-2 and cSNARF-1 Quin 2, Mag-indo 1, Mag-fura 2 (furaptra), Mag-fura 5, Indo IFF, Fura 2FF, Indo PE3, Fura PE3, Bis-fura 2, Ci₈-fura 2, FIP18, FFP18, Benzothiaza-1, Benzothiaza-2, Fluo-LR, Fluo 4, Fluo 5N, Mag-fiuo 4, Calcium green-2, Calcium green-5N, Calcium orange, Calcium orange-5N, Calcium crimson, Oregon green BAPTA 488-1, Oregon green BAPTA 488-2, Oregon green BAPTA 488-5N, Fura red, X-rhod 1, Rhod 5N, X-rhod 5N, Mag-rhod 2, Mag-X-rhod 1, Calcium green Ci₈, Fura-indoline-Ci₈, Mag-Fura-2 and Mag-Fura-3; Zr(IV)-EDT A-oxine, boronic acid compounds, thioureido naphthalene derivatives and coumarin derivatives; sodium-binding benzofuran isophthalate; and OsteoSense.

36. A kit according to any of claims 30 to 35, further comprising an excitation source.

37. A kit according to claim 36, wherein the excitation source comprises at least one of an LED, a lamp and a laser.

38. A kit according to any of claims 30-37, further including a set of control surfaces.

39. A kit according to any of claims 30-38, further including a set of control materials.