UCSF

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.