Luminescence assisted caries excavation

Details Luminescence assisted caries excavation Luminescence assisted caries excavation

2001-04-16

2004-08-03

Wilson, John J (Department: 3732)

Dentistry

Apparatus

Having means to emit radiation or facilitate viewing of the...

C433S215000

Reexamination Certificate

active

06769911

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for facilitating the removal of substantially all the bacterially invaded tooth substance in a carious region, e.g., prior to placing a restoration in an affected area (i.e., enamel and dentin) of a tooth. More particularly, the present invention relates to an improved method and apparatus for the luminescent detection of the bacterially invaded tooth substance in a carious region during removal thereof to facilitate removal of substantially all of the bacterially invaded tooth substance, while providing maximum preservation of healthy tooth structure.
2. Description of the Related Art
To effect caries excavation, e.g., prior to positioning a restoration, the dentist must differentiate between carious tooth substance which will be removed and sound tooth substance which will be conserved. Currently several methods of differentiating between carious and non-carious tooth substance are available.
One available method utilizes the hardness differential between carious and non-carious tooth substance. A sharp dental explorer is utilized to probe the tooth substance and to determine if the tissue is soft or hard. Generally the soft tissue is thought to be carious, while the hard tissue is considered to be non-carious. Utilizing this technique is relatively time consuming to implement. Furthermore, this process is inaccurate (due, e.g., to the subjective analysis employed) and can therefore lead to removal of healthy (i.e., non-carious) tooth substance and can also lead to carious substance being overlooked. Additionally, probing the dentin region of the tooth close to the pulp chamber can disadvantageously lead to exposure of the pulp chamber.
Chemomechanical techniques have also been utilized to effect caries removal. Chemomechanical caries removal is effected by first mixing an appropriate compound, i.e., a compound which softens carious tooth substance. After mixing, the compound is emptied into a suitable instrument for application to the affected area of the tooth. Alternatively, the compound could be directly applied to the tooth after mixing. The carious dentin must be thickly covered with the compound and the compound must be left in place for a period of time (e.g., thirty seconds). An instrument is thereafter utilized to scrape out the softened tooth substance. The cavity is wiped clean and caries removal is checked with a probe. The steps of applying the compound and scraping away the softened tooth substance are repeated until the relevant tooth surface feels hard when probed. Finally, the cavity formed by this process may need to be adjusted with a hand or rotating instrument before a restoration may be placed. Clearly, chemomechanical caries removal is relatively time consuming and involves evaluation of caries removal using a sharp probe. As indicated above, differentiation between carious and non-carious tooth substance using a sharp probe is a subjective procedure which can produce inaccurate evaluations, therefore, the dentist may cease applying the operable compound with residual caries remaining.
A further method for distinguishing between carious and non-carious tooth substance during excavation utilizes a dye to facilitate visual differentiation between carious and non-carious tooth substance. In this technique, a dye which colors carious tooth substance, but not sound tooth substance is applied to a tooth which has been dried by compressed air. Since only the external surface of the tooth will be dyed, continuous re-application of the dye is necessary. Furthermore, dyes have been found to inaccurately color non-carious tooth substance, leading to unnecessary removal of sound tooth substance.
Problematically, the above-identified techniques for differentiating between carious and non-carious tooth substance while effecting caries removal, (e.g., to prepare a tooth to receive a restoration) are cumbersome, time consuming, and generally either do not provide for removal of substantially all of the carious tooth substance at an affected site, or may lead to removal of non-carious tooth substance. If all of the carious material is not removed, the bacteria and carious material that remain (i.e., residual caries) can become recurrent caries.
It is known to utilize fluorescence to differentiate between carious and non-carious tooth substance in a laboratory setting. A histological slice of an extracted tooth is made so that tooth fluorescence can be evaluated under a microscope. Furthermore, it is known to evaluate the fluorescence of teeth to identify early caries from outside a tooth utilizing a computational device to evaluate tooth fluorescence in an attempt to evaluate the presence or absence of caries in a tooth. In one known device, a laser diode provides pulsed light to be directed onto the tooth. Fluorescent light stimulated by the light provided by the laser diode is translated through a handpiece for evaluation by a computational device. The computational device is connected to a display utilized to indicate a numerical output based on the emitted fluorescent light.
Additionally, visual inspection of tooth fluorescence in the red region of the spectrum has been proposed to detect early stage caries. This visual detection has been utilized in conjunction with a laser treatment device to remove early stage caries in tooth enamel. This known device utilizes a cutoff wavelength of 620 nm in evaluating tooth fluorescence so that the early stage caries are displayed as bright spots in the red region of the visible spectrum. This known device utilizes an excitation radiation in the spectral range of 360 to 580 nm to cause tooth fluorescence. To effect treatment of early stage caries in tooth enamel, the intensity of radiation of the emitted light (utilized to cause tooth fluorescence) is increased to a sufficiently strong intensity to cause the early stage caries to die out.
Furthermore, attempts have been made to utilize visual inspection of tooth fluorescence for the detection of caries during treatment (i.e., drilling) of a tooth. In procedures of this type, a discrete light source (e.g., an argon laser) is utilized to direct a luminous beam at a tooth during treatment (i.e., drilling) of the tooth. Procedures of this type are difficult to implement because two discrete devices (i.e., the drill and the light source) must be concurrently placed in or near the mouth during treatment. In an effort to simplify use of these devices, a fiber optic lead is sometimes attached to the light source, and a clip is utilized to selectively affix the fiber optic lead to the dental handpiece containing the drill. This arrangement does not overcome the deficiencies of this device, as the dentist must still manipulate two devices (i.e., the laser, and the drill) and, problematically, the connections (e.g., power cords) of these devices may become tangled during treatment. Additionally, the discrete light source of this device is not well balanced and, to the contrary, is relatively weighty at the rear of the device. Therefore this device (i.e., the light source) cannot easily be balanced in the hand nor can this device be manipulated with any degree of precision. The method of caries removal utilized with this device indicates that caries will appear dark during fluorescence of tooth substance and that excavation of the dark areas of a fluorescent tooth should be removed to effect caries removal.
What is needed in the art is an apparatus and method for utilizing visual inspection of the luminescence of the substance of a tooth (e.g., enamel and dentin) during caries removal to facilitate accurate removal of substantially all of the bacterially invaded tooth substance in a carious region during the preparation of a tooth, e.g., for placing a restoration, which apparatus and method is relatively easy to implement.
What is further needed in the art is a method for identifying bacterially invaded tooth substance in a carious region via visual inspection of the luminescenc

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