Evaluation of enamel demineralization and remineralization using near infrared imaging

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...