Dentistry – Apparatus – Having means to emit radiation or facilitate viewing of the...
Reexamination Certificate
2000-05-09
2001-05-15
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Apparatus
Having means to emit radiation or facilitate viewing of the...
C433S215000, C433S229000
Reexamination Certificate
active
06231338
ABSTRACT:
The invention relates to a method and apparatus for the detection of carious activity of a carious lesion in a tooth, comprising a light source for illuminating the tooth, and a detection device for the registration of the fluorescence radiation of the tooth.
Such a method and apparatus is disclosed in the American patent specification U.S. Pat. No. 4.515.476. In the known apparatus a fibre cable is connected to the light source, by means of which light of a predetermined wavelength or range of wavelengths is beamed in the direction of the tooth to be examined. Said light may be emitted by a laser source or a light source whose light is conducted through a filter. The light rays emitted by the tooth as a result of fluorescence are detected and are conducted through a further filter for the determination of the fluorescence radiation, whereby the range of wavelengths of the emitting light source is filtered out. The difference in fluorescence radiation then makes it possible to distinguish between the portions of teeth that are affected by carious lesion and the portions of teeth that are healthy.
It is indeed possible to identify and detect carious lesions by means of the apparatus mentioned in the preamble, however, a problem of the known apparatus is that it does not provide any information on whether it is a carious lesion that requires treatment. The person skilled in the art is aware of the fact that caries starts as demineralization of the surface of the tooth which may progressively lead to discolouring of the surface of the tooth, to its softening, and finally, to the development of a cavity. At the moment the carious lesion is discovered, either with or without the application of the apparatus disclosed in U.S. Pat. No. 4.515.476, it is not known whether a quickly developing demineralization or a slow process of demineralization and remineralization is involved. The type and the nature of the lesion determine the desired method of treatment. As mentioned just now, a carious lesion may recover as a result of remineralization. Therefore, if the detected lesion is one that is already provided with a remineralized coating, an adapted and less extensive treatment will suffice.
It is the object of the invention, to provide an apparatus as referred to in the preamble, with which it is possible in a very short time, and in any case, during a visit at the dentist's, to determine whether the examined lesion is an active lesion without coating, or an inactive lesion already provided with a remineralized coating. On this basis the correct method of treatment can then be selected.
To this end the apparatus according to the invention is characterized, in that a drying device is provided for a controlled drying of the tooth and in that the detection device is equipped to register changes in time of the tooth's fluorescence radiation. It has been shown that drying the tooth changes the fluorescence radiation. Drying and the resulting water loss causes the fluorescence radiation of the tooth to decrease, showing the difference between the healthy portion of the tooth and the portion of the tooth affected by carious lesion. It has been shown, that an active lesion loses more water and dries more quickly than healthy enamel, while an inactive lesion that is provided with a remineralized surface coating, dries more slowly, so that the apparatus according to the invention thus provides means by which the nature and severity of the lesion can be determined.
In one preferred embodiment the apparatus according to the invention is characterized, in that the detection device is equipped to register the curve of the fluorescence radiation in relation to the operational duration of the drying appliance. This provides an accurate picture of the curve of the tooth's fluorescence radiation, and consequently of the nature and severity of the carious lesion, due to the fact that the difference can be seen in the effect that a particular drying process has on the examined tooth.
The apparatus may be designed such that in order to obtain personalized results, first a calibration is carried out on healthy tooth enamel of the person examined by drying the enamel with the drying appliance and simultaneously determining and storing the curve of fluorescence radiation with the detection device. Then a similar operation can be carried out on the carious lesion to determine its carious activity.
In the apparatus according to the invention it is, however, preferred that the drying appliance and the detection device be equipped for the simultaneous drying of a first tooth portion having a carious lesion and a second tooth portion that is lesion-free, and for the simultaneous registration of the curve in time of the fluorescence radiation of the first and the second tooth portion. This makes it possible to further reduce the measuring time required for the determination of carious activity of the examined tooth.
It is possible to allow the drying operation of the tooth to occur by natural loss of moisture in the atmosphere. However, according to the invention it is preferred that a drying appliance be provided that carries out the drying operation of the examined tooth in a controlled manner, for example, by supplying a constant air flow of a predetermined volume per minute. The controlled drying may be simply carried out such that the operational duration of the drying appliance is set at a predetermined value.
In another aspect of the invention the apparatus is characterized, in that the operational duration of the drying appliance depends on the extent to which the fluorescence radiation of a tooth portion that is lesion free, changes. This avoids the tooth enamel being subjected to extensive drying, which could have an adverse effect on the quality of the tooth enamel.
In a further aspect of the invention the apparatus is characterized, in that the detection device is equipped to determine the ratio r of the fluorescence radiation of the first and the second tooth portion, and for the registration of the curve of said ratio r in time to indicate the lesion and the nature of the lesion. Therefore, a very suitable embodiment is characterized, in that the detection device is equipped to determine the time derivative of the ratio r, and in that the apparatus is further provided with an indicator for, subject to said derivative, indicating whether the lesion is active or inactive. This is a simple manner of establishing the quality of the examined carious lesion. Because the ratio r becoming an active lesion without a remineralized surface coating is—within the operational duration of the drying appliance—at an undetermined minimum, its determination provides a good indication of the respective carious activity.
In yet another aspect of the invention the apparatus is characterized, in that the detection device is equipped for the determination of the halftime of the fluorescence radiation of the first and second tooth portion, and in that the apparatus is further provided with an indicator for indicating, subject to the a half times, whether the lesion is active or inactive. This halftime provides the clear indication of the quality of the enamel, and the nature of the possibly present lesion.
The invention is also embodied in a method for the determination of carious activity of a carious lesion in a tooth, wherein the tooth is illuminated, and the fluorescence radiation of the tooth is detected, and which is characterized, in that the tooth is subjected to drying and that the change in time of the fluorescence radiation of the tooth is registered.
REFERENCES:
patent: 4215698 (1980-08-01), Nuwayser
patent: 4790751 (1988-12-01), Reinhardt et al.
patent: 5040539 (1991-08-01), Schmitt et al.
patent: 6053731 (2000-04-01), Heckenberger
de Jong Elbert de Josselin
van der Veen Monique Harriët
Vos Eeuwe-Jan
Inspektor Research Systems B.V.
Kinney & Lange , P.A.
Lucchesi Nicholas D.
LandOfFree
Method and apparatus for the detection of carious activity... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for the detection of carious activity..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for the detection of carious activity... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509203