Surface characteristics and staining of experimental visible light-cured unfilled resins

This experiment was designed to study the internal colour change of five experimental visible light-cured (VLC) resins and to deduce the relationship between staining and the physicochemical properties of the resins and a glass. The staining of the materials was measured colorimetrically, with immersion in two types of staining solution (Oil Orange or Food Red 3) for 70 days at 37°C. The water sorption, contact angle and zeta-potential of these samples were also measured. With the Oil Orange dye a positive relationship was observed only between staining and the contact angles, whereas with Food Red 3 dye a positive relationship was observed between staining and the zeta-potential and between staining and the water sorption. The results could allow a comparison of the relative contributions to staining made by physicochemical forces for the samples tested.