EP2209415A1

EP2209415A1 - Device for detecting signs of bacterial infection of teeth

Info

Publication number: EP2209415A1
Application number: EP08838281A
Authority: EP
Inventors: Thomas Hennig
Original assignee: Ferton Holding SA
Current assignee: Ferton Holding SA
Priority date: 2007-10-01
Filing date: 2008-10-01
Publication date: 2010-07-28
Also published as: WO2009046922A1; WO2009046922A8; US8456636B2; US20100216087A1; DE102007047067A1

Abstract

The invention relates to a device for detecting signs of bacterial infection of teeth, comprising a light source (18), a receiving unit (20), an evaluation unit (28), coupled to the receiving unit (20), at least one emission fiber (14), coupled to the light source (18), and at least one detection fiber (16), coupled to the receiving unit (20). The invention is characterized in that both the emission (14) and detection fiber (16) have an acceptance angle of more than 35°.

Description

Device for detecting bacterial infestation of teeth

The invention relates to a device for detecting bacterial infestation of teeth according to the preamble of claim 1.

Such a device is known for example from DE-A-42 00 741. The document discloses an apparatus for detecting caries on teeth, comprising a lighting unit which emits radiation in the wavelength range from 360 to 580 nm to a tooth. A filter transmits the fluorescence radiation returned by the tooth in a wavelength range greater than 620 nm. The transmitted radiation is evaluated for caries detection.

From DE-A-195 41 686 a further device for detecting bacterial infestation is known in which a light source emits excitation radiation in a wavelength range between 600 and 670 nm to a tooth to be examined. The fluorescence radiation produced on the tooth is recorded and evaluated in a wavelength range between 670 and 800 nm.

In the previously known devices, the substantially axial exit of the radiation from the respective optical fiber cable proved to be disadvantageous, since due to the substantially axial radiation exit sufficient irradiation straight sections narrow cavities, such as periodontal pockets, is not possible. For this reason, in the previously known devices additional optical elements provided at the radiation exit end of the optical fiber cable, which can represent a significant manufacturing effort and can significantly increase the overall diameter of the optical fiber cable.

The invention is therefore an object of the invention to provide a device of the type described above, are better detectable in the bacterially affected areas of narrow cavities, such as periodontal pockets without additional optical elements.

To solve this problem serve the features of claim 1.

The invention advantageously provides that in a device of the type described in the introduction with a light source, a receiving unit, an evaluation unit, which is coupled to the receiving unit, at least one emission fiber, which is coupled to the light source, and at least one detection fiber , which is coupled to the receiving unit, both the emission and the detection fibers have an acceptance angle greater than 35 °.

Alternatively, the acceptance angle of the emission and detection fibers may be greater than 40 °, preferably greater than 45 °.

The emission and detection fibers can be guided within a fiber optic cable.

The acceptance angle greater than 35 ° corresponds to an opening angle of at least 70 °. The advantage of an acceptance angle of greater than 35 ° is that a bundle of emission and detection fibers of the present invention is suitable for irradiating also straight sections of narrow cavities without having to use additional optical elements. The maximum intensity achieved laterally relative to the light exit surface is substantially higher in the case of emission and detection fibers according to the invention which have an acceptance angle greater than 35 ° than in conventional quartz glass optical fibers which are not wide-angle light guides. In addition, the present device according to the invention has easy handling. The emission and detection fibers can be coated one or more times.

The numerical aperture of the light source may be greater than or equal to the numerical aperture of the at least one emission fiber.

The light source used may be an LED chip.

LEDs, in contrast to lasers, emit light in a wide opening angle. Conventional, mounted on a substrate, LED chips radiate in this way circular in all directions.

The transmission of light in an optical waveguide essentially takes place without changing the aperture angle, that is to say that the light has the same aperture angle on exiting the optical waveguide as it did on entry.

In order to thus realize light with a wide opening angle at the light guide exit side, in a further exemplary embodiment coupling is dispensed with optical lenses and a distance of less than 0.3 mm, preferably nearly 0 mm, between the LED chip and the proximal end face of the emission fiber, intended.

By dispensing with optical lenses significantly more opening angle can be realized.

Between the LED chip and the proximal end surface of the at least one emission fiber, a medium may be arranged which has a refractive index which lies between that of the emission fiber and that of the surface of the LED chip. In this way, the reflection losses at the transitions are minimized. Advantageously, the introduced into the space medium is optically transparent.

In a further development, the proximal end face of the emission fibers adjoining the light-emitting surface of the LED chip is smaller than the light emission. surface of the LED chip and completely covered by the light-emitting surface of the LED chip.

In a further embodiment, the LED chip emits light in the UV range and / or in the adjacent visible range, preferably violet light in the wavelength range from 390 to 420 nm. The radiation in this wavelength range can be particularly efficient the optical differences between healthy and bacterially affected teeth discover.

The distal end face of the bundle of emission and detection fibers may be coupled to the proximal end face of at least one light guide element, wherein the light guide element made of sapphire or a mineral material or plastic and may have an acceptance angle greater than 35 °. The acceptance angle can also be greater than 40 °, preferably greater than 45 °. The light guide can be uncoated, single or multiple coated.

The at least one light-guiding element can be guided within an inspection probe, which has a shaft and a coupling part. The inspection probe can be connected to a handpiece. The shaft can be rigid or flexible. The shaft can also be bent or made flexible.

Also, the light guide can be rigid or flexible.

The at least one light-guiding element can guide the excitation radiation emitted by the light source via the emission fibers to the tooth and also the fluorescence radiation emanating from the tooth.

The light-guiding element may consist of a single optical fiber or of a plurality of optical fibers, i. consist of a bundle of optical fibers.

The overall diameter of the light guide element may be greater than or equal to the total diameter of emission and detection fibers. The distal end face of the bundle of emission and detection fibers and the proximal end face of the light guide element can be pressed against each other with the aid of a spring force.

The proximal end face of the light-guiding element and the distal end face of the bundle of emission and detection fibers can each have a crowned surface.

As an alternative to the light guide, the emission and detection fibers may be directly, i. be performed without interposition of an additional light guide to the tooth. The emission and detection fibers can also be guided at the distal end within an inspection probe with shaft and coupling part.

The two aforementioned embodiments with inspection probe facilitate handling, since the bundle of emission and detection fibers or the light guide due to the curved shaft easily in z. B. periodontal pockets can be introduced.

The emission and detection fibers may terminate with the distal end of the shaft or protrude a maximum of about 5 cm from the shaft.

In a further embodiment, it is provided that the proximal end of the inspection probe can be connected to a handpiece, wherein the emission and detection fibers are guided within the handpiece. In the embodiment where an additional light guide is coupled to the bundle of emission and detection fibers, the juncture between the bundle of emission and detection fibers and the light guide may be within the handpiece.

This has the advantage that the device is easier to handle, since the bundle of emission and detection fibers, or the light guide can be performed better due to the handpiece.

The light source may be disposed within the handpiece. In a further development, it is provided that the length of the at least one emission fiber or the total length of the emission fiber and the light element is less than 60 cm, preferably less than 10 cm.

These embodiments have the advantage that the emitted light does not have to travel long distances from the light source to the tooth, since in the case of wide-angle light guides, the intensity of the radiation decreases considerably with increasing length of the transmission path.

In a further development, it is provided that the receiving unit has a semiconductor sensor arrangement in which three sensors are arranged within a surface. The three sensors detect the fluorescence radiation excited at the tooth via the at least one emission fiber and returned via the detection fiber in three separate wavelength ranges. The at least one detection fiber may be arranged centrally above the semiconductor sensor arrangement at a defined distance from the surface of the semiconductor sensor arrangement.

The light cone emerging from the proximal end of the detection fiber illuminates the sensor area of the semiconductor sensor arrangement without interposing optical lenses.

In the prior art, there is the disadvantage that it can lead to incorrect results in a study in the field of various dental filling materials. Especially in the transition region of Zahnrnaterial to restorative material is an information as to whether a tooth is infected bacterially or not, of particular interest.

The invention has the advantage that the sensors used detect the fluorescence radiation excited on the tooth in three separate wavelength ranges and an evaluation unit evaluates them. Because of the multitude of tissues present in the mouth and different restorative materials, a diagnosis based on the analysis of three spectral regions is much more accurate and reliable. Another advantage over the prior art is that the returned radiation does not need to be routed via separate optical fiber cables to different optical receivers, or has to be split among the optical receivers via mirrors or other optical elements. Also, no optical elements, in particular lenses are needed to illuminate the sensor surface.

The detection fiber is fixed by means of a light guide holder centrally above the semiconductor sensor arrangement and at a defined distance from the surface of the semiconductor sensor arrangement, wherein the light guide holder is attached to the housing of the semiconductor sensor arrangement.

The three sensors can be sensors for radiation, each of which lies in the wavelength range of the primary colors red, green and blue. The three sensors can also be sensors for radiation in other wavelength ranges, eg. B. radiations in the wavelength range of mixed colors.

The sensors can be arranged within a circular area and the respective base color or mixed color can be assigned a circular area segment of 120 °.

This embodiment has the advantage that the returned radiation is uniformly distributed to the sensors, since the detection fiber is positioned centric to the semiconductor sensor array.

However, the three sensors are not limited to being arranged inside a circle but may be arranged arbitrarily with each other.

The sensor for radiations in the wavelength range of the primary color red has the highest sensitivity and is sensitive to at least 750 nm.

This has the advantage that the weak compared to the green fluorescence red fluorescence is amplified, thereby reducing electrical crosstalk is reduced. An optical pre-filter for suppressing the excitation radiation can be arranged between the at least one detection fiber and the semiconductor sensor arrangement and fixed on the semiconductor sensor arrangement with the aid of an optically transparent potting compound.

The thickness of the optical pre-filter may be less than 2 mm. The pre-filter may be a dielectric filter.

Also, the semiconductor sensor assembly may be disposed on a circuit board which is shielded with a copper layer against electromagnetic radiation.

Alternatively, any layer that shields against electromagnetic radiation may be used.

It can be arranged between the receiving unit and the evaluation three separate amplifier for amplifying the respective signals of the sensors.

Data sets in the form of three-dimensional measured values can be stored in the evaluation unit, wherein the evaluation unit compares the measured values measured with the stored data sets and outputs a result with regard to the bacterial infestation of examined tooth sections.

Also, the fluorescence signals of the light-guiding element can be detected by the three sensors of the semiconductor sensor arrangement. By comparing the measurement signals generated by the three sensors with reference data sets of different materials stored in the evaluation unit, the material of the light-guiding element can additionally be recognized, wherein the evaluation unit outputs the material of which the light-guiding element consists.

The information of which material the light-guiding element consists can be passed on to a software. Among other things, this software determines the sensitivity with which the measured values are evaluated. The passing on of the information to the software has the advantage that the sensitivity of the measurement can be adapted to the material of the light-guiding element. That means that the Sensitivity, with which the measured values are evaluated, can be adapted to the application.

In the following, embodiments of the invention will be explained in more detail with reference to the drawings:

They show schematically:

1 is a schematic block diagram of the device according to the invention,

2a shows a wide-angle light guide whose axis is parallel to a tooth surface,

2b is a quartz glass optical fiber, which is not a wide-angle light guide, and whose axis is aligned parallel to a tooth surface,

3 is a representation with light distribution on the flat surface of Fig. 2a and Fig. 2b,

4 is a diagram showing the relationship between attenuation of the illuminance and length of the light guide,

5 is an illustration in which the light source is an LED chip,

6 is a schematic block diagram in which the light source is arranged in the handpiece,

7 shows a device with semiconductor sensor arrangement,

8 shows a block diagram of the device with receiving unit, amplifier, subtractor, evaluation unit and display,

9 shows a device with a light guide. Fig. 1 shows a schematic block diagram of the device according to the invention. Excitation radiation from the light source 18 is coupled into a bundle of emission fibers 14 and transported by them to a tooth 1. The emission fibers 14 are guided together with a bundle of detection fibers 16 in an optical fiber cable 12. The fiber optic cable 12 is coupled to a handpiece 10 at the distal end. The emission fibers 14 and the detection fibers 16 are guided in the handpiece 10 and in an inspection probe 2. The inspection probe 2 consists of a coupling part 6 and a shaft 4. The proximal end of the coupling part 6 can be connected to the distal end of the handpiece 10. The shaft 4 may preferably be made of metal or plastic. The fluorescence radiation excited at the tooth 1 by the excitation radiation is transported via the detection fibers 16 to a receiving unit 20. The emission and detection fibers 14, 16 preferably terminate at the distal end 8 with the distal end of the shaft 4. At most, the emission and detection fibers 14, 16 protrude by about 5 cm from the shaft 4.

In the receiving unit 20, the fluorescence radiation is detected in three separate wavelength ranges and converted into three electrical signals. These are fed via separate preamplifier 22 to a lock-in amplifier 24. By means of the lock-in amplifier 24 downstream subtractor 26 background signals can be subtracted. Background signals are produced by reflection of the excitation radiation at the distal end 8 of the emission and detection fibers 14, 16 and by a slight intrinsic fluorescence of the optical fibers and the adhesives used. The size of this signal is directly proportional to the excitation radiation. If the excitation radiation is kept constant, the result is a constant offset signal. This background signal is measured during the switch-on routine of the measuring device and eliminated in the subtracter 26 before the evaluation. Within the evaluation unit 28 is a memory 27 in which three-dimensional measured values of healthy tooth material, diseased tooth material and artificial filling material are stored. Three-dimensional means that for each measured value, the radiation intensities in three spectral ranges z. B. in the spectral regions of the primary colors red, green, blue are measured. The currently measured three-dimensional measured value is compared with the stored comparison measured values and a ratio is calculated. This relationship is in the form of values a display unit 29 is displayed. The user knows that if this value is smaller than a certain value, the examined tooth area is free from bacterial residues.

FIGS. 2a and 2b show a first optical fiber bundle 14, 16 and a second optical fiber bundle 19, each having emission and detection fibers. Both the first optical fiber bundle 14, 16 and the second optical fiber bundle 19 are guided within a shaft 4. The respective shaft 4 is located, as shown in FIGS. 2a and 2b can be seen, between gum 31 and tooth 1. In the two figures, the two light cones, which throw the first and second optical fiber bundles 14, 16, 19, drawn with dashed lines. FIG. 2a shows a light cone of the optical fiber bundle 14, 16, which represents a bundle of wide-angle light guides. Fig. 2b shows in comparison to the light cone of a bundle of conventional quartz glass optical fibers, which are not wide-angle light guides. The central axes 34, 36 of the first and second optical fiber bundles 14, 16, 19 are at a distance of, for example, 300 μm parallel to the tooth surface 1 a, which is essentially flat in this section. The diameters of the first and second Lichtleitbündels 14, 16, 19 amount to 210 microns in the embodiments shown. The wide-angle light guides radiate the light with an opening angle of 120 °, which corresponds to an acceptance angle of 60 °. The conventional quartz glass optical fibers, which are not wide-angle optical fibers, have an aperture angle of e.g. 25 °. In Figure 2a, the gum is close to the tooth. Nevertheless, since wide-angle optical fibers have been used, it is still possible to examine the surface of the tooth. With conventional quartz glass optical fibers with a typical opening angle of 25 °, illumination in a narrow periodontal pocket would not be possible. Quartz glass light guides, which are not wide-angle light guides, can be used (see FIG. 2 b) only if the space between tooth and gum, ie the periodontal pocket, is substantially larger than in FIG. 2 a.

Glass waveguides having an acceptance angle greater than 35 °, preferably greater than 40 °, are preferably used as the wide-angle optical fiber. However, it is also possible to use wide-angle plastic optical fibers, preferably polystyrene. Fig. 3 shows the light intensity distributions in an experimental setup on a flat surface (instead of the tooth surface Ia with gums) under geometrical conditions similar to those of Figs. 2a and 2b correspond. The optical fibers and the planar surface are arranged at the same distances and in the same orientations to each other as the optical fiber bundles 14, 16 and the tooth surface Ia in Fig. 2a and Fig. 2b, the difference is that the optical fibers of the experimental arrangement not in one Gingival pocket light up and therefore the light rays are not limited by the gums. The light rays can hit the flat surface unhindered. The light exit surface, ie the free end of the light guide lies on the abscissa at the value 0. The white dots represent the light intensity distribution for conventional quartz glass light guides with an opening angle of 25 °, the black squares represent the light intensity distribution for wide-angle light guides with an opening angle of 120 °. Significant differences between the two curves can be seen. An opening angle of only 25 ° leads to a flat curve. The highest light intensity on the flat surface is approximately in the range between 1.5 mm and 2 mm in front of the light exit surface of the light guide. In the case of an opening angle of 120 °, the highest light intensity achieved on the flat surface is only about 0.3 mm in front of the light guide. The maximum intensity achieved on the flat surface is more than five times higher in the case of the wide-angle optical fiber used in a device according to the invention compared to the maximum intensity of a conventional quartz glass optical fiber, which is not a wide-angle optical fiber. This means that much more accurate measured values can be determined, since the signal-to-noise ratio is significantly better. In the case of a wide-angle optical waveguide, as is evident from FIGS. 2 a and 2b, the examined surface section is considerably shorter and better illuminated than with conventional quartz glass optical waveguides which are not wide-angle optical waveguides. The ratio of bacterially contaminated area to area under investigation has a direct influence on the measured values, ie, if the bacterially contaminated area is small compared to the surface area under investigation, the contamination is difficult because of the small percentage of contaminated area to the total area surveyed read from the measured values. Small impurities can therefore easily be overlooked when using conventional quartz glass optical fibers having a large surface area under inspection and low illumination, as shown in FIG. For wide-angle light guides with relatively short surface area and intense illumination, the ratio of contaminated area to area section under investigation is more favorable in terms of the percentage, so that contaminated areas are more clearly and accurately detectable. For this reason, the tooth sections to be examined, in particular in narrow cavities, can be examined more precisely with a wide-angle light guide according to the invention.

Fig. 4 shows the illuminance at the end of various optical fibers relative to the illuminance at the input of the optical fibers as a function of their length. The relative illuminance was calculated according to the following formula:

B = NA ² * 1 (T ^{((a * i) / I0)}

B: Illuminance

NA: numerical aperture a: attenuation of the optical fiber in dB / m

L: length of the light guide in m

The open circles refer to a wide-angle optical fiber with an opening angle of 120 °. This wide-angle optical fiber has an attenuation of about 17 dB / m in the range of 400 nm. The black dots refer to a quartz glass fiber with an opening angle of 25 °. This quartz glass optical fiber has an attenuation of about 0.1 dB / m in the range of 400 nm.

It can be seen from FIG. 4 that long optical fibers, especially in the case of wide-angle light guides, lead to a weakening of the light available at the exit surface in the short-wave spectral range around 390-420 nm, which is interesting for fluorescence excitation. The optical fiber should, in order to avoid this attenuation, have a length of less than 60 cm, preferably less than 10 cm, when using a wide-angle optical fiber. It can be seen from FIG. 4 that with wide-angle light guides which are shorter than 10 cm, an approximately 10-fold higher illuminance can be achieved at the light exit side than with conventional quartz glass optical waveguides which are not wide-angle light guides. Looking at Fig. 3 and Fig. 4, it can be summarized that an approximately 50 times higher light intensity can be achieved on a surface of a substance to be examined, which runs parallel to the axis of the wide-angle optical fiber. It can be seen from FIG. 3 that in the case of wide-angle light guides, an approximately 5 times higher light intensity can be achieved on a surface of a substance to be examined which runs parallel to the axis of the wide-angle light guide than with non-wide-angle light guides. From FIG. 4 it can be seen that an approximately 10 times higher illuminance, or in other words light intensity, can be achieved at the light exit surface. It follows that when using a wide-angle optical fiber shorter than 10 cm, a 50 times higher light intensity can be obtained on a surface of a substance to be examined which is parallel to the axis of the wide-angle optical fiber.

FIG. 5 shows an LED chip 40, which is coupled opposite to the emission fibers 14. That is, less than 0.3 mm, preferably 0 mm, spacing remains between the LED chip surface and the proximal end face of the emission fibers 14. Between the LED chip surface and the emission fibers 14, a non-illustrated, preferably transparent medium, for. As a synthetic resin, be arranged, the calculation index between which the E- missionsfasern 14 and the LED chip surface is located. With the help of the transparent medium, z. B. a curable plastic, the emission fibers are mechanically fixed to the LED chip 40 and optically coupled. The LED chip 40 is mounted by means of an electrically conductive adhesive 46 on a monitor diode chip 50 and electrically contacted. The monitor 50 supplies a measured variable proportional to the optical output line of the LED chip 40. From an electrical contact point 48, a bonding wire 44 is connected to an electrical connecting pin 54 which is guided insulated in the socket 52. The monitor diode 50 has a second electrical contact, which is guided as Gehäusepin 56 to the outside. The LED chip also has a second electrical connection, this takes place via a bonding wire 42, which is connected to an isolated in the base 52 outboard electrical connection pin 58. Alternatively, the structure of FIG. 5 can also be executed without a monitor diode 50. In this case, the electrical contact point 48 and the bonding wire 44 with the isolated in the socket pin 54 would be omitted.

So that the radiation losses of the excitation radiation can be kept low, in one exemplary embodiment, in FIG. 6, which is similar to the exemplary embodiment from FIG. 1, the light source is arranged within the handpiece 10. This has the advantage that the length of the emission fibers 14 is very short executable. The emission and detection fibers 14, 16 are brought together at the distal end of the handpiece 10. At the distal end, an inspection probe with shaft and coupling part connects, in which the emission and detection fibers 14, 16 are guided. Distally, the emission and detection fibers terminate with the distal end of the shaft. The fluorescence radiation excited at the tooth 1 is transmitted from the tooth 1 via the detection fibers 16 to a receiving unit 20 which is located in the device 17. The detection fibers 16 are guided from the proximal end of the handpiece 10 to the receiving unit in the optical fiber cable 13. In Fig. 6, the light source of Fig. 5 is used.

FIG. 7 shows a bundle of detection fibers 16, which are positioned centrally via a semiconductor sensor arrangement 62 according to the invention and at a defined distance from the surface of the semiconductor sensor arrangement 62 with the aid of a light guide holder 68. The optical fiber holder 68, which is not shown here, attached to the housing of the semiconductor sensor assembly 62. The semiconductor sensor arrangement 62 has three sensors, which are arranged within a circle, which detect the fluorescence radiation excited in the tooth via the emission fibers 14 in three separate wavelength ranges and convert them into three electrical signals. The three sensors are sensors z. B. for the primary colors red, green and blue. The respective primary color is assigned a circle segment of 120 °. The distance between the end face of the detection fibers 16 and the surface of the semiconductor sensor array 62 ensures complete illumination of the three sensors. The distance between the end face of the detection fibers 16 and the surface of the semiconductor sensor array 62 can be less than 2 mm when using wide-angle light guides. Between the detection fibers 16 and the semiconductor sensor arrangement 62, a pre-filter 64 for suppressing the excitation radiation can be applied. orders be. The pre-filter 64 is fixed on the semiconductor sensor assembly 62 by means of an optically transparent potting compound.

Fig. 8 shows a block diagram of the device according to the invention. The detection fibers 16 which guide the radiation returned by the tooth are positioned centrally via a semiconductor sensor arrangement 62 at a defined distance from the surface of the semiconductor sensor arrangement 62. The semiconductor sensor arrangement 62 has three sensors arranged within a circle, which detect the fluorescence radiation excited on the tooth or in the periodontal pocket via the emission fibers 14 in three separate wavelength ranges and convert them into three electrical signals. These are, as also shown in FIG. 1, fed via separate preamplifiers 22, a lock-in amplifier 24 and a subtracter 26 to an evaluation unit 28. There, the measured values are compared with comparison measured values stored in a memory 27 and a value is output which can be displayed on a display 29. If the value is above a certain value, it means that the tooth has bacterial infestation.

FIG. 9 shows a block diagram which is very similar to that of FIG. 6, with the difference that the end face of the bundle of emission and detection fibers 14, 16 is coupled to the end face of a light element 9.

The light guide 9 is guided within a centering device 15 and projects at the proximal end of the centering device 15 out of this. The centering device 15 and thus the light-guiding element 9 are pressed against the bundle of emission and detection fibers 14, 16 within a plug-in and coupling element 11 by a spring. Such a plug and coupling element 11 may be a commercially available ST plug having a bayonet mount. The plug-in and coupling element 11 is located within a handpiece 10. The light-guiding element 9 is pushed back into the coupling part 6 by the length projecting beyond the proximal end of the centering device 11. Since the light-guiding element 9 is fixed or glued within the shaft 4 and / or the distal end of the coupling part 6, the light-guiding element 9, which in this case is a flexible plastic optical fiber, bends inside the coupling part 6. The light-guiding element 9 stands by the bend under a bias in the longitudinal direction, which causes the light-guiding element 9 is pressed permanently against the bundle of emission and detection fibers 14, 16. This ensures a good coupling of the radiation from the bundle of emission and detection fibers 14, 16 into the light-guiding element 9 and vice versa.

At the junction, the excitation radiation from the emission fiber 14 is coupled into the light guide element 9. The light-guiding element 9 is guided within an inspection probe 2 with shaft 4 and a coupling part 6. The light-guiding element 9 can terminate at the distal end with the distal end of the shaft 4 or protrude distally therefrom, protruding a maximum of 30 mm out of the shaft 4. The shaft 4 may be closed distally either open or for reasons of hygiene with an optically transparent element. The optical element may consist of either glass, plastic or the like. Also, the optical element may be a lens. The light exiting distally from the light-guiding element 9 illuminates the tooth section to be examined. The light returned by the illuminated tooth section is picked up by the distal end of the light-guiding element 9 and guided via the detection fibers 16 to a receiving unit 20.

Alternatively, the light guide 9 may also consist of sapphire or other mineral materials. The connection between the light-guiding element 9 and the bundle of emission and detection fibers 14, 16 can also take place without bending the light-conducting element 9, in particular if the light-guiding element 9 is rigid. The light-guiding element 9 and the bundle of emission and detection fibers 14, 16 may have a crowned end face in order to allow a better coupling of the light.

Also, the Lichtleiteiement 9 consist of several optical fibers, ie the light guide consists of a bundle of optical fibers. These light guides may each have a diameter of about 30 microns. Also, these optical fibers may consist of sapphire or other mineral materials or plastics. In addition, the fluorescence signals of the light-guiding element 9 can be detected by the receiving unit 20 for the fluorescence signals of the illuminated tooth sections. These latter fluorescence signals are then also converted into electrical signals. These are fed to the evaluation unit 28 via separate preamplifiers 22, a lock-in amplifier 24 and a subtractor 26. In the memory 27, which is located within the evaluation unit 28, can additionally three-dimensional measured values of the materials of various possible üchtleitelemente 9 are located. The measured fluorescence signals of the light-guiding element 9 can be compared with the stored measured values. In this way it can be determined from which material the light-guiding element 9 is made. The sensitivity of the measurement can be adapted to the material of the light-guiding element.

Claims

claims

1. A device for detecting bacterial infestation of teeth, with

a light source (18),

a receiving unit (20),

an evaluation unit (28) which is coupled to the receiving unit (20),

at least one emission fiber (14) coupled to the light source (18) and at least one detection fiber (16) coupled to the receiving unit (20),

characterized ,

that both the emission (14) and the detection fiber (16) have an acceptance angle greater than 35 °.

2. Apparatus according to claim 1, characterized in that the acceptance angle of the emission and Detektionsfasem (14, 16) is greater than 40 °, preferably greater than 45 °.

3. Device according to one of the preceding claims, characterized in that the numerical aperture of the light source (18) is greater than or equal to the numerical aperture of the at least one emission fiber (14).

4. Device according to one of the preceding claims, characterized in that the light source (18) is an LED chip.

5. The device according to claim 4, characterized in that between the LED chip and the proximal end face of the at least one emission fiber (14) is a distance of less than 0.3 mm, preferably 0 mm.

6. Apparatus according to claim 4 or 5, characterized in that between see the LED chip and the proximal end face of the at least one emission fiber (14) is arranged a medium having a refractive index which is between that of the emission fiber (14) and the surface of the LED chip.

7. Device according to one of claims 4 to 6, characterized in that the adjacent to the light emitting surface of the LED chip proximal end face of the emission fiber (14) is completely covered by the light emitting surface of the LED chip.

8. Device according to one of claims 4 to 7, characterized in that the LED chip light in the UV range and / or visible range, preferably violet light in the wavelength range of 390 nm to 420 nm, emitted.

9. Device according to one of the preceding claims, characterized in that the entire distal end face of a bundle of emission and Detektfonsfasern (14, 16) with the proximal end face of at least one light guide element (9) is coupled, wherein the light guide (9) of the excitation radiation emitted by the light source (18) via the emission fibers (14) to the tooth (1) and also the fluorescence radiation emanating from the tooth (1)

10. The device according to claim 9, characterized in that the light guide element (9), which consists of a single light guide or of a bundle of light guides, an acceptance angle greater than 35 °, preferably greater than 40 °.

11. The device according to claim 9 or 10, characterized in that the light guide element (9) within an inspection probe (2) is guided, which has a shaft (4) and a coupling part (6).

12. Device according to one of claims 9 to 11, characterized in that the distal end face of the bundle of emission and Detektionsfa- sem (14, 16) and the proximal end face light-guiding element (9) by means of a spring force are pressed together.

13. Device according to one of claims 9 to 12, characterized in that the proximal end face of the light guide element (9) and the distal end face of the bundle of emission and detection fibers (14, 16) each have a spherical surface.

14. Device according to one of claims 1 to 8, characterized in that the emission (14) and detection fibers (16) are guided at the distal end within an inspection probe (2) with shank (4) and coupling part (6).

15. Device according to one of the preceding claims, characterized in that the length of the at least one emission fiber (14) or the total length of the at least one emission fiber (14) and the at least one light guide element (9) less than 60 cm, preferably less than 10 cm , is.

16. Device according to one of claims 11 to 15, characterized in that the proximal end of the inspection probe (2) can be connected to a handpiece (10), the emission (14) and detection fibers (16) being arranged within the handpiece (10). are guided and / or that the junction between the bundle of emission (14) and detection fibers (16) and the light guide (9) is located within the handpiece (10).

17. The apparatus according to claim 16, characterized in that the light source (18) within the handpiece (10) is arranged.

18. Device according to one of the preceding claims, characterized in that the receiving unit (20) comprises a semiconductor sensor arrangement (62), are arranged in the three sensors within a surface, which stimulated the tooth on the at least one emission fiber (14) and over the detection fiber (16) detects fluorescence radiation sent back in three separate wavelength ranges. sen, wherein the emerging from the proximal end of the detection fiber (16) light cone without interposition of optical lenses illuminates the sensor surface of the semiconductor sensor assembly (62).

19. The device according to claim 18, characterized in that a preferably dielectric, optical pre-filter for suppressing the excitation radiation between the at least one detection fiber (16) and the semiconductor sensor array (62) is arranged and on the semiconductor sensor array (62) by means of an optically transparent potting compound is fixed.

20. Device according to one of claims 15 to 19, characterized in that data sets in the form of three-dimensional measured values are stored in the evaluation unit (28), wherein the evaluation unit compares the measured values measured with the stored data sets and a result with regard to the bacterial infestation of an examined one Teeth section outputs.