Purpose: The purpose of this investigation was to examine the changes in wettability of dental impression materials during setting. This study compared the properties of the initial water contact of two different dental impression materials and their subsequent development during polymerization. Materials and Methods: Two dental impression materials (Impregum Penta Soft and Aquasil) with different chemical compositions (polyether and polyvinyl siloxane, respectively) were investigated with respect to their changing wetting properties by time-resolved static contact angle measurements. Ten sets of measurements each were taken over a period of 400 seconds with 150 points of data each; the first pictures were used for further characterization of the initial interaction. Results: With 73 degrees, Impregum Penta Soft exhibited a significantly lower contact angle, which stayed lower during the process of setting, compared to the silicone-based material. The initial interaction of the droplet showed a repulsive interaction of Aquasil with the water droplet. Conclusion: Impregum Penta Soft showed a more hydrophilic behavior during the process of setting compared to Aquasil and can therefore be expected to exhibit better flow properties. The method of time-resolved static contact angle measurements is a well-suited analytic instrument to monitor temporally changing wetting phenomena. Int J Prosthodont 2003;16:49–53.