Abstract
PURPOSE: The study uses near-infrared imaging at 1310 nm to acquire high contrast
images of early enamel demineralization and subsequent remineralization (i.e. "white
spot lesions" and "remineralized lesions"). The specific aims are: 1) to test the
hypothesis that we can measure differences in optical contrast at 1310 nm between sound
and artificially demineralized/remineralized enamel on the buccal and occlusal surfaces
of teeth; and 2) to test the hypothesis that NIR imaging manifests greater contrast than
other methods, such as qualitative light fluorescence and cross-polarization visible
reflectance.
METHODS: 16 human tooth samples were used in this study. Teeth were painted with a
clear varnish, leaving a 2x2 window on the buccal and occlusal surfaces for
demineralization. Teeth were imaged with the following methods: Transillumination -
NIR with polarization; reflected light - NIR with cross polarization; Quantitative Light
Fluorescence; and reflected light after periods of demineralization and remineralization.
RESULTS: All of the imaging techniques showed an increase in contrast during the
demineralization periods and the remineralization periods. NIR imaging with cross
polarization offered the highest contrast during the periods of demineralization and a
decrease during the remineralization but did not statistically differ from the other
methods.
CONCLUSIONS: NIR imaging can detect demineralization and remineralization in
enamel. It can become a useful tool in for non destructive monitoring of white spot
lesions during orthodontic treatment.