Methods: Ten experimental resin-based restorative materials were prepared. Material ST representing a common formulation for resin-based restorative materials was used as the control. ST was modified with an experimental methacrylate carrier agent or a zeolith carrier, which were loaded with two different polydimethylsiloxanes respectively resulting in the materials A to G. The materials H and I were compounded by replacing certain amounts of the standard monomer blend with a polymerizable silicone polyether acrylate.
Twenty discs (diameter 10 ± 0.1 mm, thickness 1 ± 0.1 mm) of each material were prepared and polymerized for 40 s from each side. One half was stored dry for 24h; the surfaces of the other half of the specimens were stored in water (7d, 37°C) and polished subsequently with fine and superfine polishing-discs (Super-Snap mini, Shofu Inc., Kyoto, Japan). The contact angle Θ of water on the materials was determined measuring ten times on each specimen with the sessile drop method (Phoenix-Alpha contact angle goniometer, Surface Electro Optics (SEO) Corporation, Suwon-City, Korea).
Results: After 24h except for H and I all materials showed a significantly higher contact angle and thus more hydrophobicity than ST(p<0.05). Water storage and polishing resulted in significantly higher contact angles for all materials compared to their values after dry storage (p<0.05) and for all materials a highly significant difference compared to ST (p<0.001).
Conclusions: A new method of incorporating surface-active ingredients could be demonstrated. Surface characteristics of resin composites could be changed into more hydrophobic, which could be implemented in new materials to modify initial biofilm accumulation.
This research was supported by Deutsche Forschungsgemeinschaft (RU825/1).