Room: Exhibit Hall | Forum 9
Purpose: The purpose of this work was to characterize optically bovine tooth at dry and wet conditions by using near-IR optical coherence tomography (OCT), providing theoretical and practical considerations to support OCT as potential tool for estimating accurately optical parameters of dental tissue.
Methods: Bovine incisors were imaged by using a swept source OCT operating at 1300 nm, which was configured to acquire 800-1200 B-scans with lateral dimension in 2 mm at a scan rate of 16 kHz. Dentin and enamel samples were conserved in water at 25 ÂºC. Then, OCT images of samples at wet condition were acquired. Next, samples were dried for 1 hour in an oven at 80 oC and then new OCT images were acquired. In the analysis, the exponential decay of light in the tissue was corrected taking into account the contribution of the beam divergence to the OCT signal. In addition, we also consider practical aspects such as samples thickness, electrical OCT noise, spot size and Rayleigh range, and interface reflections and speckles contribution to avoid biased results.
Results: The refractive index of bovine dentin and enamel is 1.60 Â± 0.01 for both of them. The uncorrected values of the extinction coefficients of dry dentin and enamel are 25.4 Â± 2.4 cm-1 and 5.7 Â± 1.2 cm-1, respectively, while the corrected are 24.3 Â± 2.6 cm-1 and 3.1 Â± 0.6 cm-1. For wet condition, we obtained a value of 13.2 Â± 1.8 cm-1 for dentin, while for enamel it is 2.1 Â± 0.7 cm-1.
Conclusion: The OCT imaging modality was used to measure the extinction coefficients of bovine dentin and enamel under dry and wet conditions. Our study showed significant differences in the extinction coefficient of enamel and dentin under dry and wet conditions.
Funding Support, Disclosures, and Conflict of Interest: The authors acknowledge FAPESP (2015/05684-0 for DRTS) and CAPES for the grants and fellowships given to this research.
Optical Imaging, Quantitative Imaging