title: Terahertz time-domain spectroscopy for monitoring the curing of dental composites.
abstract: We apply terahertz (THz) time-domain spectroscopy for monitoring the curing process of three different light-curing dental composites. Exact knowledge of the sample thickness is required for a precise determination of the THz dielectric parameters, as the materials exhibit shrinkage when they are cured. We find very small but significant changes of the THz refractive index and absorption coefficient during stepwise light exposure. The changes in the refractive index are correlated with changes in the density of the materials. Furthermore, the refractive index and the sample thickness are found to give the most reliable result for monitoring the curing process of the dental composites.
authors.affiliation: Fachbereich Physik, Philipps Universität Marburg, 35032 Marburg,  Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwerdtfeger
authors.forename: Sina
authors.initials: S
authors.lastname: Lippert
authors.forename: Martin
authors.initials: M
authors.lastname: Koch
authors.forename: Andreas
authors.initials: A
authors.lastname: Berg
authors.forename: Stefan
authors.initials: S
authors.lastname: Katletz
authors.forename: Karin
authors.initials: K
authors.lastname: Wiesauer