Nondestructive assessment of the inhibition of demineralization with PS-OCT

Polarization sensitive optical coherence tomography (PS-OCT) is a new non-destructive imaging method that can be used to assess the severity of demineralization on tooth surfaces. Objectives: The purpose of this study was to use PS-OCT to measure the inhibition of demineralization on enamel and dentin surfaces after topical fluoride treatments and high intensity laser irradiation. Methods: Human enamel (n=10) and dentin (n=20) blocks were prepared from extracted teeth and three linear incisions were produced on each sample by laser irradiation. After treatment the center of each sample was covered with acid resistant varnish to serve as a negative control with and without a laser treated area. Topical fluoride was applied to the left side of each sample to serve as the fluoride only and laser + fluoride treatment groups and nothing was added to the right side, for the laser only + lesion only groups, for a total of 6 groups per sample. After laser irradiation and topical fluoride application samples were exposed to demineralization solutions and subsequently scanned with a PS-OCT system to determine the integrated reflectivity in each sample area. After scanning, samples were sectioned and examined using polarized light microscopy and microradiography for comparison. Results: PS-OCT was able to measure significant reductions (p<0.05) in the integrated reflectivity between the treatment groups due to inhibition by either fluoride alone (dentin), the laser alone (enamel) or laser + fluoride (enamel + dentin) even though the laser modification of enamel and dentin surfaces caused changes in the optical reflectivity. Conclusions: PS-OCT has great potential for the clinical assessment of caries inhibition after chemical and laser intervention. Supported by NIH/NIDCR Grant R01-DE17869.