DE102013226777A1 - Observation unit for detection of fluorescence and this comprehensive device for the detection of caries - Google Patents

Abstract

An observation unit (3) for detecting fluorescence has at least one filter element (5) which has at least one first and at least one second transmission characteristic (8), the first and the second transmission characteristic (8) differing.

Description

Technical area

The invention relates to an observation unit for the detection of fluorescence, which has at least one filter element, and a device comprising this observation unit for the detection of caries.

State of the art

In the treatment of carious cavities, it is essential to remove all carious sites of a tooth. In order to facilitate or simplify the diagnosis of carious sites, the different fluorescence properties of carious and healthy tooth substance are frequently used. When the tooth substance is excited with light of a suitable wavelength, typically between 360 and 580 nm, for example approximately 400-410 nm, the spontaneously emitted light of the carious regions differs markedly from that emitted by healthy regions. While the fluorescence of the carious sites lies in the red wavelength range, the healthy tooth substance fluoresces in the green wavelength range.

From the DE 42 00 741 A1 a device is known which uses these fluorescence properties to detect caries on teeth and optionally also to treat directly. For this purpose, the device has a lighting device, for example a beam source with a radiation filter, which only transmits the desired excitation wavelength. Furthermore, the device comprises an edge or band filter, which reflects or absorbs all wavelengths which are smaller than a cut-off wavelength of about 620 nm, and optionally also all wavelengths which are greater than a cut-off wavelength of about 720 nm. This filter is mounted in a spectacle frame, whereby the person wearing the spectacles, the hands free for further activities and is not limited in the observation of fluorescence in the viewpoint and / or the movement of the head.

However, it is not possible with the glasses described to detect the green fluorescence of the healthy tooth substance, since the corresponding frequency ranges are filtered out by the mounted filter.

To be able to perceive both the green and the red fluorescence, for example, edge or long-pass filters are used with a correspondingly lower cut-off wavelength of, for example, 520 nm, as for example from US 6,325,623 B1 and the US 2003/022126 is known.

In order to distinguish the fluorescence of healthy and carious tooth substance better, a combination of bandpass and edge or long pass filter can be used. Such a filter may, for example, be light in the wavelength range of the fluorescence of the healthy tooth substance, e.g. 500-570 nm, as well as wavelengths greater than 600 nm as completely as possible or at least partially pass and filter out all the smaller or intermediate wavelengths.

Compared to a pure edge or long-pass filter, such a combined filter achieves a greater contrast in terms of fluorescence properties, which facilitates distinguishing between healthy and carious tooth substance. This is particularly desirable for reliable control. The disadvantage, however, is that such a combined filter produces an overall darker image than a pure long-pass filter, as a result of which physical structures in the image area are less recognizable. This is disadvantageous in particular during a machining of a tooth, for example during an excavation. During editing, a brighter picture would be desirable.

The object of the present invention is to provide an observation unit for the detection of carious tooth substances, which provides both a fluorescence as high-contrast as possible and the brightest possible image of one or more excited to spontaneous emission teeth.

Presentation of the invention

The invention relates to a fluorescence detection observation unit comprising a filter element having at least first and second transmission characteristics, the first and second transmission characteristics differing.

In the treatment of teeth, for example, to distinguish between carious and healthy tooth substance whose different fluorescence properties can be exploited. For this purpose, the teeth are illuminated with light having a wavelength that stimulates the fluorescence, the teeth, on the one hand, reflecting this excitation light and, further, in healthy areas, typically emitting green light, e.g. between 480 nm and 560 nm, and in carious areas typically red light, e.g. between 630 nm and 790 nm, due to fluorescence emission.

Recognition of these different fluorescences, especially of caries-affected sites, can be achieved by the use of a suitable method Filter element simplified or improved. Filter element refers to a means with any special optical filter characteristic, so a special transmission properties for light. The filter characteristic shows the transmittance as a function of the wavelength. This can range from complete transmission to complete blocking by reflection or absorption.

Since with fluorescence excitation the intensity of the reflected excitation light is usually significantly greater than that of the fluorescence, for example, filtering out the excitation light by means of a filter element with a suitable transmission property in an observation beam path can significantly simplify the detection of the fluorescence.

Furthermore, with a fluorescence excitation of teeth, the green fluorescence of the healthy tooth areas is typically more than twice as intense as the red fluorescence of the carious areas, therefore attenuating the green fluorescence by means of a filter element with suitable transmission property can greatly facilitate the detection of the carious area.

A complete filtering out of the green fluorescence of the healthy tooth areas by means of a filter element with a corresponding transmission property is likewise possible. However, the contrast between the red and the green fluorescence is particularly high and the distinction between red and green is particularly simple for the human eye, in particular higher than a contrast of red fluorescence to darkness. Therefore, at least partial retention of green fluorescence in the viewing beam path may facilitate detection of the carious sites.

Overall, the filtering out of light reduces the light intensity and thus the impression of brightness that an observer can gain. This can make the recognition of physical structures, such as the external shape of a tooth, more difficult. Therefore, for certain operations in the treatment of a tooth, it is again more advantageous to filter out or absorb or reflect as little light as possible or no light.

For example, it may be desirable during a diagnostic step to view a tooth through a filter element with a specific filter effect and to have no filter effect in the observation beam path during a processing step, for example an excavation.

The combination according to the invention of at least two different transmission properties in a filter element makes it possible in a simple manner to provide all the desired filter properties without it being necessary to change or remove the observation unit. In this case, the first as well as the second transmission properties can each be one of the aforementioned filter properties or any other filter property.

Advantageously, the filter element has at least a first region with the first transmission characteristic and a second region with the second transmission characteristic.

Locally disposing the different transmission characteristics within a filter element allows the observer to look through the at least one first or at least one second area solely by moving the head and / or the viewing angle and / or the filter element, thereby selecting the most suitable transmission property ,

The choice of the number of different transmission properties and the corresponding number of different areas depends essentially on a desired application, a size of the filter element and a necessary minimum size of the individual areas.

Advantageously, the filter element has a transition region between the first and the second region. The transition region advantageously has a transmission characteristic which has a graduated course from the first transmission property to the second transmission property.

The transition region makes it possible to make the transition from a first to a second transmission property. In particular, a graduated course allows a smooth transition in the image impression and avoids disturbing image effects that can occur due to a sharp edge when changing from at least one first transmission characteristic to at least one second transmission characteristic.

Advantageously, the filter element has an electrochromic layer.

This can be changed by means of a current and / or voltage change between the at least two different transmission properties of the filter element.

The filter element may for example consist of plastic or glass, which is coated with an electrochromic layer. Or an electrochromic layer can be arranged between two glass or plastic layers. Electrochromic layer denotes a layer which can also be subdivided into further layers and has electrochromic properties, ie the transmission property of this layer changes with a suitable change of an applied current or an applied voltage.

Furthermore, for example, a battery or a connection to a voltage source can be arranged on the observation unit and can be connected to the electrochromic layer via a control unit, for example a rotary potentiometer. For example, by changing the voltage applied to the electrochromic layer, the transmission property of this layer can be changed.

This makes it possible to equip an observation unit with a filter element, which always has exactly one transmission property, wherein, for example, by means of an electrical circuit very easily between at least two different transmission properties can be changed without having to change the observation unit for this purpose.

Advantageously, the observation unit has a sensor for detecting light of a wavelength and a control unit for controlling a voltage applied to the electrochromic layer.

This allows the automatic regulation of the transmission property. For example, upon detection of excitation light by the sensor, a desired filter characteristic can be automatically activated by automatically controlling the voltage or current at the electrochromic layer by means of the control unit so that the filter element has the desired transmission property. If no excitation light is detected by the sensor, the current or the voltage on the electrochromic layer can be regulated or switched off, for example, by means of the control unit such that the filter element has a desired, for example, no filtering effect.

Advantageously, the filter element has a thin dielectric layer.

By reflection and transmission on a thin dielectric layer occur due to the path difference of various reflected and transmitted light components constructive and destructive interference. Such filters are often referred to as interference filters. The thickness of the dielectric layer is typically smaller than the wavelength of the light to be filtered.

The interference occurring on thin layers are angle-dependent, so that different transmission properties occur by means of a thin dielectric layer for different angles of incidence of light on the layer. Thereby, the thin dielectric layer makes it possible to provide at least two transmission properties of the filter element, for example, over the entire filter element, whereby a user can choose between the different transmission properties by changing the viewing angle, for example by moving the head, gaze and / or filter element.

Again, such a thin dielectric layer may be constructed of several different layers to have the desired transmission characteristics.

Advantageously, the at least one filter element has at least one further transmission characteristic, which differs from the first and the second transmission characteristic.

One or more further transmission properties with the first and second transmission properties in FIG

Combining a filter element allows multiple filter properties to be provided in a single observation unit.

Advantageously, the first or the second or the further transmission characteristic has an edge wavelength, wherein light having a wavelength which is smaller than the edge wavelength is absorbed or reflected and wherein light having a wavelength which is greater than the first edge wavelength is transmitted.

The edge wavelength thus denotes the filter-specific wavelength, which separates an absorption region and a transmission region from one another. Filters with such transmission properties or such an edge wavelength are often referred to as edge filters or as long-pass filters.

If the first or the second or also a further transmission property of the filter element is a long-pass filter, it is possible to filter out in particular the excitation light, which is more energy-rich than the fluorescence and therefore has a shorter wavelength, and at the same time ensure, with a suitable choice of the edge wavelength, that all Fluorescence or at least the desired wavelengths are transmitted as completely as possible.

Advantageously, the edge wavelength is between 490 nm and 520 nm.

Such an edge wavelength makes it possible to filter out the reflected excitation light, which for example typically has a wavelength around 400 nm for teeth, and at the same time to ensure that the fluorescence transmits as completely as possible and arrives at the observer.

Advantageously, the first or the second or the further transmission characteristic has an edge wavelength and a stopband, wherein light having a wavelength which is smaller than the edge wavelength or in the stopband is absorbed or reflected and wherein light having a wavelength which is greater than that Edge wavelength is and is not in the stopband, is transmitted.

Such a transmission property allows, for example, a good visibility of the fluorescence of carious tooth areas. By means of the edge wavelength or the filter effect corresponding to a long-pass filter, the short-wavelength excitation light and by means of the band-stop filter the light with wavelengths between the green fluorescence of healthy tooth substance and the red fluorescence of carious tooth substance is filtered out. Thus, essentially only the green and the red fluorescence remain in the observation beam path, whereby these are to be distinguished from one another particularly well by the human eye. In particular, the red areas, ie the areas affected by caries, are clearly visible.

Advantageously, the edge wavelength is between 490 nm and 520 nm, whereby short-wave excitation light can be removed from an observation beam path.

Advantageously, the blocking range is between 560 nm and 600 nm, whereby light with wavelengths in the range between the fluorescence of healthy and carious tooth substance is removable.

Advantageously, the first or the second or the further transmission characteristic has a damping region, wherein at least a portion of light having a wavelength in the damping region is absorbed.

This allows, for example, a high-contrast representation of carious areas by additionally attenuating the green fluorescence of the healthy tooth areas, so that it remains only partially in the illumination beam path. The attenuation is necessary because the fluorescence of the healthy tooth area otherwise dominates because the intensity of this fluorescence is significantly greater than the intensity of the fluorescence of the carious tooth area and because the areas of healthy tooth substance are usually larger in area than the caries-infected areas.

Advantageously, the attenuation range is between 500 nm and 560 nm and the proportion is 50%.

As a result, in particular the fluorescence of healthy tooth substance is attenuated to such an extent that the remaining intensity is comparable to the intensity of the fluorescence of carious tooth substance and an image impression optimized for caries detection is generated.

Advantageously, the first, the second or the further transmission characteristic is designed so that light of any wavelength is completely transmitted.

This makes it possible to provide an impression of an observed object without filter effect without changing the observation unit. For example, when working on the tooth, it may be advantageous to observe the tooth without further filtering effects and thereby better recognize the physical structure of the tooth.

Advantageously, the observation unit is a pair of glasses and comprises a spectacle frame on which the filter element is mounted.

Glasses with filter elements mounted therein allow observation of an object, for example a tooth, by the observation unit, in particular by the filter element, without being limited in freedom of movement, in particular the hands being free to carry out further activities.

Advantageously, the observation unit comprises a holder, with which the filter element is foldably mounted on a pair of glasses.

This makes it easy to fold away, for example, up, should it not be needed.

Advantageously, the observation unit comprises a holder with which the filter element can be attached to a dental handpiece.

As a result, the observation unit can be used without it being extra to hold it with one hand.

Furthermore, the invention relates to a device for detecting caries with a lighting unit for exciting fluorescence, wherein the device is an inventive Observation unit for detection of fluorescence includes.

The illumination unit can be, for example, a hand-held light probe or a light source unit mounted on a spectacle frame, for example on the spectacle frame comprising a spectacle frame, or with a corresponding holder on the head.

Brief description of the drawings

The invention will be explained with reference to the drawings. It shows that

1 a device for detecting caries, the

2 a trained as glasses observation unit having a first and a second region, each having a different transmission property, the

3a -D different transmission properties

4 an observation unit with a transition area, the

5a , b a filter element with an electrochromic layer, the

6 a filter element with a thin dielectric layer, the

7 an observation unit arranged on a dental instrument and the

8th a hinged on a spectacle frame observation unit.

embodiment

The 1 shows a device 1 for caries detection, which is a lighting unit designed as a light probe 2 and an observation unit 3 includes. The observation unit 3 is set as glasses with a glasses 4 and filter elements 5 educated.

The filter elements 5 the observation unit 3 can like in 2 show a first and a second area 6 . 7 have, wherein the first area 6 a first transmission property 8th and the second area 7 a second transmission property 8th having.

In 3 are different transmission properties 8th shown as a filter characteristic. In each case the transmission is plotted as a function of the wavelength λ.

3a shows a filter characteristic of an edge filter with an edge wavelength 9 , Such a transmission property 8th is particularly suitable for filtering out light used for excitation of fluorescence by absorption or reflection and thereby being able to better recognize the excited fluorescence. A filter element 5 with this transmission characteristic typically has a yellow color.

3b shows a filter characteristic of a filter element 5 with a slow transition from complete absorption or reflection to complete transmission.

In 3c a filter characteristic is shown that has an edge wavelength 9 , a damping area 10 and a restricted area 11 having. Such a transmission property 8th is particularly adapted to the easy detection of carious tooth areas, whereby the excitation light for the fluorescence is filtered out and the fluorescence of healthy tooth substance is weakened. A filter element 5 with these transmission properties typically the color is orange.

3d shows a filter characteristic of a completely transparent medium. A filter element 5 with this transmission characteristic is typically clear.

In a filter element 5 besides the in 3 shown transmission properties 8th also other transmission properties 8th , which are advantageous for a desired application, as a first, second or further transmission property 8th a filter element 5 be implemented.

This in 2 illustrated filter element 5 for example, a first area 6 with a transmission property 8th according to 3a and a second area 7 with a transmission property 8th according to 3d exhibit.

It is also possible that a filter element 5 three or more areas, each with different transmission properties 8th has, for example, with a first transmission property according to 3d , a second transmission characteristic according to 3a and another transmission property according to 3c ,

The filter elements 5 can be between a first area 6 and a second area 7 also a transition area 12 exhibit, as in 4 is shown. The transition area 12 For example, a transmission property 8th according to 3b exhibit. This may make the transition between the first and second regions, for example when the first region has a first transmission characteristic according to FIG 3a and the second transmission property according to 3c having. The transition area 12 but can also be a continuously or in the smallest possible stages of the first transmission property 8th of the first area 7 to the second transmission property 8th of the second area 8th changing transmission property 8th exhibit. As a result, edges are in transition from a transmission property 8th avoided to another.

In 5a is an observation unit designed as glasses 3 shown in a spectacle frame 4 mounted filter elements 5 with an electrochromic layer 13 , one on the glasses frame 4 attached battery 14 as well as one on the spectacle frame 4 attached potentiometer 15 having. The electrochromic layer 13 is between a base material 16 , For example, plastic or glass, and arranged over the potentiometer 15 with the battery 14 connected. By means of the potentiometer 15 can be attached to the electrochromic layer 13 applied voltage can be changed, thereby increasing the transmission property 8th the electrochromic layer changes. In this way, by means of a first position of the potentiometer 15 or a first applied voltage, a first transmission property 8th and by means of a second position of the potentiometer 15 or a correspondingly applied second voltage, a second transmission property 8th of the filter element 5 be achieved.

It would also be possible instead of a battery 14 on the spectacle frame 4 to provide a connection for a current or voltage supply. These could then be connected for example via a cable, a battery which is attached to a holder, such as a clip, with which it can be attached, for example, at the edge of a trouser pocket.

Switching between different transmission properties 8th the electrochromic layer 13 and thus the filter element 5 can, for example, by turning the potentiometer 15 or by one on the spectacle frame 4 arranged switch / key etc. take place.

But it is also possible, an automatic control of the transmission property 8th provide over the voltage or the current. For this purpose, for example, a control unit 17 and a sensor 18 , For example, a photodiode, placed on the glasses 4 which is suitable for detecting light used for excitation of fluorescence, as shown in FIG 5b outlined. Detects the photodiode 18 no excitation light, so the voltage or the current through the control unit 17 at the electrochromic layer 13 regulated so that it has a first transmission property, such as no filter effect, the filter element 5 So for example, a transmission property 8th according to 3d having. Once the photodiode 18 Excitation light detected, the voltage or the current at the electrochromic layer 13 by means of the control unit 17 adjusted so that the electrochromic layer 13 a second transmission characteristic, for example the desired transmission property 8th to detect the fluorescence. This may, for example, a transmission property 8th according to 3a or 3c be.

In 6 is a filter element 5 represented, which is a basic material 16 and a thin dielectric layer 19 having. The thin dielectric layer 19 causes an incident or viewing angle dependent transmission property 8th , For light incident at a first angle of incidence α1, the filter element faces 5 with the thin dielectric layer 19 , a first transmission property 8th for example according to 3a on. For light incident at a second angle of incidence α2, the filter element faces 5 on the other hand, a second transmission property 8th , for example, according to 3c on.

The thin dielectric layer 19 For example, it may also be designed so that it transmits a third transmission characteristic, for example, according to FIG. 3, for light which lies at a third angle of incidence α3 which lies between the first and second angles of incidence α1 and α2 3b having.

So can by means of a thin dielectric layer 19 for an incident angle α1, a transmission property 8th according to 3a , for an incident angle α3 a transmission property 8th according to 3b and for an incident angle α2, a transmission property according to 3c will be realized. This allows a user by changing the viewing angle or the orientation of the observation unit 3 between these different transmission properties 8th to choose or change.

As in 7 the observation unit can be represented 3 also a filter element 5 and a holder 20 and by means of the holder 20 to a dental hand instrument 21 , for example, the in 1 illustrated light probe 2 or a file or a drill, etc. be attached or attached.

It is also possible the observation unit 3 with a foldable attitude 22 For example, to arrange a pair of glasses, so that the Observation unit can be folded away as needed, as in 8th is shown.

LIST OF REFERENCE NUMBERS

1

Device for the detection of caries

2

lighting unit

3

observation unit

4

Brillengestell

5

filter element

6

first area

7

second area

8th

transmission property

9

Edge wavelength

10

attenuation range

11

stopband

12

Transition area

13

electrochromic layer

14

battery

15

potentiometer

16

base material

17

control unit

18

sensor

19

thin dielectric layer

20

bracket

21

dental hand instrument

22

foldable bracket

α1

angle of incidence

α2

angle of incidence

α3

angle of incidence

λ

wavelength

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4200741 A1 [0003]
• US 6325623 B1 [0005]
• US 2003/022126 [0005]

Claims (20)

Observation unit ( 3 ) for the detection of fluorescence, characterized in that the observation unit ( 3 ) at least one filter element ( 5 ), which has at least one first and at least one second transmission property ( 8th ), wherein the first and second transmission properties ( 8th ). Observation unit ( 3 ) according to claim 1, characterized in that the filter element ( 5 ) at least a first area ( 6 ) with the first transmission property ( 8th ) and at least one second area ( 7 ) with the second transmission property ( 8th ) having. Observation unit ( 3 ) according to claim 2, characterized in that the filter element ( 5 ) between the first and the second area ( 6 . 7 ) a transitional area ( 12 ) having. Observation unit ( 3 ) according to claim 3, characterized in that the transition region ( 12 ) a transmission property ( 8th ) having a graduated course from the first transmission property ( 8th ) to the second transmission property ( 8th ) having. Observation unit ( 3 ) according to claim 1, characterized in that the filter element ( 5 ) an electrochromic layer ( 13 ) having. Observation unit ( 3 ) according to claim 5, characterized in that the observation unit ( 3 ) a sensor ( 18 ) for detecting light of a wavelength (λ) and a control unit ( 17 ) for controlling a at the electrochromic layer ( 13 ) has applied voltage. Observation unit ( 3 ) according to claim 1, characterized in that the filter element ( 5 ) a thin dielectric layer ( 19 ) having. Observation unit ( 3 ) according to one of claims 1 to 7, characterized in that the at least one filter element ( 5 ) at least one further transmission property ( 8th ), which differ from the first and second transmission properties ( 8th ) is different. Observation unit ( 3 ) according to one of claims 1 to 8, characterized in that the first or the second or the further transmission property ( 8th ) an edge wavelength ( 9 ), wherein light having a wavelength (λ) which is smaller than the edge wavelength ( 9 ), is absorbed or reflected, and wherein light having a wavelength (λ) greater than the first edge wavelength ( 9 ) is transmitted. Observation unit ( 3 ) according to claim 9, characterized in that the edge wavelength ( 9 ) is between 490 nm and 520 nm. Observation unit ( 3 ) according to one of claims 1 to 10, characterized in that the first or the second or the further transmission property ( 8th ) an edge wavelength ( 9 ) and a blocking area ( 11 ), wherein light having a wavelength (λ) which is smaller than the edge wavelength ( 9 ), is absorbed or reflected and wherein light having a wavelength (λ) greater than the edge wavelength ( 9 ) is transmitted, and wherein light having a wavelength in the stopband ( 11 ) is absorbed or reflected. Observation unit ( 3 ) according to claim 11, characterized in that the edge wavelength ( 9 ) is between 490 nm and 520 nm. Observation unit ( 3 ) according to claim 11 or 12, characterized in that the blocking area ( 11 ) is between 560 nm and 600 nm. Observation unit ( 3 ) according to one of claims 1 to 13, characterized in that the first or the second or the further transmission property ( 8th ) a damping area ( 10 ), wherein at least a portion of light having a wavelength (λ) in the attenuation range ( 10 ) is absorbed. Observation unit ( 3 ) according to claim 14, characterized in that the damping region ( 10 ) is between 500 nm and 560 nm and that the proportion is 50%. Observation unit ( 3 ) according to one of claims 1 to 15, characterized in that the first, the second or the further transmission property ( 8th ) is formed so that light of any wavelength (λ) is completely transmitted. Observation unit ( 3 ) according to one of claims 1 to 16, characterized in that the observation unit ( 3 ) is a pair of glasses and a spectacle frame ( 4 ), on which the filter element ( 5 ) is mounted. Observation unit ( 3 ) according to one of claims 1 to 17, characterized in that the observation unit ( 3 ) a holder ( 22 ), with which the filter element ( 5 ) is foldable mounted on a pair of glasses. Observation unit ( 3 ) according to one of claims 1 to 18, characterized in that the observation unit is a holder ( 20 ), with which the filter element ( 5 ) on a dental hand instrument ( 21 ) is attachable. Contraption ( 1 ) for the detection of caries, comprising a lighting unit ( 2 ) for the excitation of fluorescence, characterized in that the device is an observation unit ( 3 ) for detecting fluorescence according to any one of claims 1 to 19.

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