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Quantified light-induced fluorescence, review of a diagnostic tool in prevention of oral disease
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Image of FIG. 1.
FIG. 1.

QLF™ concept: a blue excitation light beam (B) with peak intensity at 405 nm illuminates a tooth; a yellow filter (F) transmits green (G) and red (R) fluoresced photons to the eye or camera.

Image of FIG. 2.
FIG. 2.

Left: white light image of a premolar visualizing an initial caries lesion visual as a white spot. See encircled area Right: fluorescence image shows GF: the white spot is now shown as a dark spot.

Image of FIG. 3.
FIG. 3.

Green Fluorescence (GF) principle shown schematically: blue photons (B) enter the tooth and scatter in enamel and fluoresce green (G) at the dentine (D) and enamel (E) junction DEJ. Where there is a white spot below in the enamel part, blue rays scatter and will not reach the DEJ; fluoresced photons will scatter back at the white spot, both effects resulting in a visual dark spot when viewed with QLF™.

Image of FIG. 4.
FIG. 4.

RF. Bacterial metabolites as in cavities and plaque or calculus on the tooth fluoresce bright red. See the areas indicated by the arrows.

Image of FIG. 5.
FIG. 5.

Red (R) and Green (G) Fluorescence schematically: the red fluorescence (RF) is caused by excitation of red extrinsic fluorophores from bacterial metabolites.

Image of FIG. 6.
FIG. 6.

Monte Carlo result of photons which scattered and fluoresced inside a tooth enamel block with inside a block of bacterial metabolites at a depth of 0.250 mm below the surface, as shown at the left top of the figure. The block in the middle shows green and red fluoresced photons that emerged out of the surface. is the number of photons used, the number of fluoresced red photons, the number of fluoresced green photons.

Image of FIG. 7.
FIG. 7.

Monte Carlo graph of the red over green number of photons (R/G) that emerged out of the surface in the enamel and bacterial metabolite model of Fig. 6.

Image of FIG. 8.
FIG. 8.

Example of sound and clean teeth as viewed with QLF™.

Image of FIG. 9.
FIG. 9.

Example of removable signs of bacterial activity. The same element before (left) and after (right) brushing. The arrows point at the areas of interest,

Image of FIG. 10.
FIG. 10.

Locations with high concentration of porphyrines are clearly visible as brightly red areas. Plaque is shown in the left image and calculus in the right one.

Image of FIG. 11.
FIG. 11.

Example of a clear white spot along the gingival margin together with (nonremovable) signs of bacterial activity inside the tooth (left, see arrow). Example of a leaking margin of a composite filling infiltrated with nonremovable plaque (middle, see arrows). Right image: area within the dotted ellipse: occlusal surface showing discoloration at the dark fissure line and signs of bacterial activity underneath the surface. After opening the fissure a dental carious lesion was found underneath.

Image of FIG. 12.
FIG. 12.

Left: example of a sound sealant: there is no RF visible at the margins of the sealants (see arrows). Right: a compromised sealant where plaque infiltrated the space between sealant and tooth (see regions indicated by the arrows).


Generic image for table
Table I.

Sensitivity and specificity for the detection of carious lesions with QLF or visual. Both methods are used subjectively.

Generic image for table
Table II.

Bacteria involved in RF.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Quantified light-induced fluorescence, review of a diagnostic tool in prevention of oral disease