Patent EA-002899-B1 (EA)
Title: Toothbrush with fluorencence means for locating dental plaque
Inventor: MULLER WERNER
IPC: A61C17/00
Filed: 1999-05-12
Abstract: 1. An apparatus for detecting biological deposits on the surface of a tooth which comprises illumination means to direct exciting radiation onto a test tooth surface, detection means to detect radiation emitted from a test tooth surface in response to the exciting radiation, means to process characteristics of the emitted radiation and to associate the characteristics with the presence of biological deposits, and to indicate the presence of biological deposits to the user, characterised by: illumination means to direct exciting radiation at a wavelength up to 530 nm onto a test tooth surface believed to have a biological deposit thereon, detection means to detect fluorescence emission from the test tooth surface at a wavelength associated with that of auto fluorescence emission from a substantially biological deposit- free tooth surface, means of converting fluorescence emission to an electrical signal, means to make a comparison of the intensity of the said fluorescence emission from the test tooth surface with an intensity of auto fluorescence emission, at a wavelength associated with that of auto fluorescence emission from a substantially biological deposit free tooth surface, from a tooth surface believed to have less biological deposit thereon than is present at the test tooth surface, means to associate a reduction in intensity of the said auto fluorescence relative to the intensity of auto fluorescence from a tooth surface known to have less biological deposit thereon than is present on the test tooth surface with the presence of biological deposits on the test tooth surface, and, indicator means to indicate the presence of such biological deposits to a user of the device. 2. An apparatus according to Claim 1 characterised in that the exciting radiation has a wavelength 420- 530 nm. 3. An apparatus according to Claim 1 or 2 characterised in that the detection means detects the fluorescence emission over a wavelength range above 520 nm. 4. An apparatus according to any one of the preceding Claims characterised in that the intensity of auto fluorescence emission from biological deposit- free or substantially biological deposit- free tooth surfaces is stored as a reference standard in the device. 5. An apparatus according to any one of the preceding Claims characterised in that it is constructed to initially measure the intensity of auto fluorescence emissions from the surface believed to be clean, and to use the said intensity as a basis for the comparison with the intensity of emission from the test tooth surface. 6. An apparatus according to any one of the preceding Claims, characterised by the detection means being moveable between locations on the user's teeth, so that in the course of this movement the exciting radiation is directed onto a plurality of tooth surfaces on the same or different teeth, the variation of fluorescence emission detected as the device moves around the user's mouth is measured, and associate the measurement thus obtained with the presence of biological deposits on the test tooth surface, and associate the measurement thus obtained with the presence of biological deposits on the test tooth surface 7. An apparatus according to Claim 6 characterised in that the device is adapted to measure the difference between highest and lowest peaks of fluorescence emission intensity and to associate changes in this difference during a process of tooth cleaning with the presence of biological deposits an the test tooth surface. 8. An apparatus according to Claim 6 or 7 characterised in that the device is adapted to measure the mean between highest and lowest peaks and to associate an increase in this difference during a process of tooth cleaning with the presence of biological deposits on the test tooth surface. 9. An apparatus according to Claim 6, 7 or 8 characterised by being constructed to ignore any fluorescence intensity peak below a specified certain minimum value. 10. An apparatus according to any one of the preceding Claims characterised by being constructed to: detect a fluorescence emission during a period of time over which the detection device moves from one tooth area to one or more other tooth areas; detect peaks in the emission intensity with time; and to measure and compare the heights of such peaks. 11. An apparatus according to Claim 10 characterised by being constructed to measure the difference between the height of the lowest and the highest peaks of fluorescence emission intensity and to associate this difference with the presence of biological deposits which are then indicated to the user. 12. An apparatus according to any preceding Claim characterised in that the device is provided with detection means to detect fluorescence emission from two spaced apart regions of tooth surface, and to compare the relative intensities of fluorescence emission from these two spaced apart surfaces, to associate any difference between the relative intensities with the presence of biological deposits on the tooth surface and to indicate the presence of such deposits to the user. 13. An apparatus according to Claim 12 characterised in that the maximum spacing apart of the two regions is the height from the junction with the gum to the crown of the tooth. 14. An apparatus according to Claim 12 or 13 characterised by two detection means positioned relative to each other so that when the device is inserted into the mouth one of the two detection means is likely to be positioned adjacent a tooth at or near the gumline and the other at or near the crown of the tooth. 15. An apparatus according to Claim 14 characterised by comprising a toothbrush head with two detection means positioned across the width of the toothbrush. 16. An apparatus according to any preceding Claim characterised by being constructed to observe the presence of, and/or measure any gradient in fluorescence emission intensity with distance across a test tooth surface as the device moves from one part of a tooth surface to another. 17. An apparatus according to Claim 16 characterised by being constructed to detect and/or measure changes in the gradient during a process of tooth cleaning. 18. An apparatus according to any preceding Claim characterised in that the apparatus additionally comprises: detection means to detect auto fluorescence emission from the test tooth surface at a wavelength associated with auto fluorescence emission from biological deposits on a tooth surface, means to relate this auto fluorescence emission to the presence of biological deposit on the test tooth surface, and indicator means to indicate the presence of biological deposit to a user of the device. 19. An apparatus according to Claim 18 characterised in that the detection means is capable of detecting auto fluorescence emission from the test tooth surface at a wavelength associated with auto fluorescence emission from dental plaque on the tooth surface. 20. An apparatus according to any preceding Claim characterised in that the exciting radiation is at a wavelength 470 +- 40 nm. 21. An apparatus according to any preceding Claim characterised by illumination means comprising a light guide for directing the exciting radiation onto a test tooth surface comprising one or more optical fibres, and the detector means comprise a light guide comprising one or more optical fibres to guide fluorescence emission from the tooth surface to a detector for the fluorescence emission radiation. 22. An apparatus according to Claim 21 characterised in that the optical fibres comprising the light guide of the illumination means and the detection means are bundled together within a suitable conduit and terminate at a common optical probe. 23. An apparatus according to Claim 21 or 22 characterised in that a greater number of fibres is used for the light guide of the emission radiation than for the excitation radiation because of the lower intensity of the fluorescence emission radiation. 24. An apparatus according to any preceding Claim characterised by a cut-off filter to prevent radiation with a wavelength below ca 420nm from reaching the tissues of the user. 25. An apparatus according to Claim 24 characterised by a dichroic mirror filter. 26. An apparatus according to any one of the preceding Claims characterised in that the excitation radiation and the detection of the fluorescent emission are modulated and/or phase locked. 27, An apparatus according to any preceding Claim characterised in that it comprises a toothbrush having the means to direct exciting radiation at the test tooth surface and the means to detect fluorescence emission from the test tooth surface incorporated into the toothbrush head. 28. An apparatus according to Claim 27 characterised by being constructed so as to indicate the initial presence of biological deposits an the surface of the user's teeth and indicate the quantitative reduction or absence of biological deposits after the teeth have been brushed for a suitable period. 29. An apparatus according to Claim 27 or 28 characterised by being constructed to indicate to the user that biological deposits are present somewhere in an area of the user's teeth, and that continued brushing of the teeth is necessary to remove the deposits.