Optical Attenuation Coefficients of Moist and Dry Tooth Determinate by Optical Coherence Tomography

We investigated cross-sectional optical coherence tomography (OCT) images to determine the attenuation coefficients of moist and dry sound bovine teeth under near-infrared laser illumination. We acquired OCT images of the samples using a commercial swept-source OCT equipment, with a central wavelength of 1300 nm. In order to determine the attenuation coefficient of the samples, we studied the attenuation of light as it traveled through the dental tissue. The method considers only backscattered light, which restricts the contributions of speckles and reflective dispersion. To minimize errors related to the OCT equipment and because the operation influences the measurements, we revised various practical details associated with the OCT technique. Our results revealed significant differences between the attenuation coefficients of the dry and moist samples. We interpreted the values measured for dry/moist dentin (24.3/13.2 cm −1 ) and dry/moist enamel (3.1 /2.1 cm −1 ) based on the optical properties of the tooth. These differences were due to modifications in the optical properties of natural tissues when water evaporates from the tooth. The measured values can help us to obtain accurate optical parameters for in vivo and in vitro optical dental diagnosis techniques and therapies that use longer wavelengths.