Correlation between Lesion Progression and Depolarization Assessed by Polarization-Sensitive Optical Coherence Tomography

The detection of early stages of caries is still one of the major challenges in preservative dentistry. Since it is known from polarized light microscopy (PLM) that intrinsic enamel birefringence is affected by demineralization, polarization-sensitive optical coherence tomography (PSOCT) could facilitate the noninvasive detection and assessment of early carious lesions. The present study aims to correlate enamel lesion progression and depolarization measurements based on PSOCT in an artificial demineralization model. A total of 18 enamel slabs were prepared from bovine incisor teeth and demineralized in an acetic buffer solution for up to 49 days. The degree of polarization (DOP)—indicating depolarization and thus, demineralization—was calculated from PSOCT measurements and compared to lesion depth which was measured from PLM images. Artificial lesions showed characteristic zones of natural enamel demineralization in PLM images. DOP representations showed no depolarization for sound, nondemineralized enamel, whereas significant changes were found after 15 days of acid-exposition. The linear regression analysis of the DOP and the measured lesion depth showed a substantial correlation ( R 2 = 0.71 ). The results indicate that PSOCT-based depolarization imaging provides an unambiguous contrast for initial enamel demineralization which is correlated to the lesion progression.