Determinations of Early Carious Lesion of Enamel Using OCT

Objectives: The purpose of this study was to determine the early carious lesion of enamel using optical coherence tomography (OCT).
Methods: Extracted human teeth were used in this study. The ethical approval was obtained from Nihon University. The specimen treated with 8% methylcellulose gel and pH 4.75 lactic acid buffer solution in order to develop artificial carious lesion, and immersed in artificial saliva 28-day. From the OCT images, the peak intensity (dB) and the 1/e² width (μm) were obtained. The integrated value in unit dB･μm was calculated based on the area of peak intensity. The data for each group were analyzed using one-way repeated measures ANOVA and Tukey-Kramer tests (α=0.05). Specimens from each condition were observed under a three-dimensional laser scanning microscope (LSM).
Results: The peak intensities in artificial carious lesion were in the value of -21.3 ~ -35.8 dB. The control surfaces revealed significant decreases in the value of -63.4 ~ -79.2 dB. The (1/e²) widths of artificial lesion were in the value of 79.2 ~ 91.6 μm, while those of varnished surface ranged 110.7 ~ 141.9 μm. The integrated values of artificial caries lesion were in the value of 3591 ~ 4728 dB･μm, while those of the control surface ranged 8779 ~ 9968 dB･μm.
Conclusions: The value of the peak intensity and (1/e²) width obtained by TD-OCT was successfully used to track the development of demineralization and test the efficacy of a detection of artificial caries lesion.