Optical properties of dentin and enamel by spectroscopic ellipsometry

Abstract

The aim of this study was to explore the extinction coefficient and refractive index of dentin and enamel from human teeth of different anatomical categories and individuals over a wide range of wavelengths. We carried out spectroscopic ellipsometry measurements on dentin and enamel in their natural geometry, investigating three groups of teeth in vitro. The refractive index ($n$) and extinction coefficient ($k$) were accessed for the $400-1000nm$ range. The results indicate that in the infrared we have lower absorption for some specific wavelengths, while the refractive index shows practically constant behavior. We observed a significant decrease in the extinction coefficient in the $815-825nm$ and $875-885nm$ ranges, even for different geometries and individuals, indicating that this wavelength range is more for suitable laser interaction with teeth in vivo to avoid heating and teeth damage. In recent years, several optical studies have been proposed for dental diagnosis, including backscattering and transillumination. However, to the best of our knowledge, a detailed study on optical properties such as refractive index $n$ and extinction coefficient $k$ for human dentin and enamel is lacking in the literature.