Fracture toughness of modified dental resin systems.

This study compared the relative fracture toughness of a Bis-GMA//TEGDMA (50:50 wt%)-based resin system modified by 5, 10, and 15 wt% of a methacrylate-terminated poly(butadiene-acrylonitrile-acrylic acid) terpolymer toughening agent. After storage in distilled water at 37 +/- 2 degrees C for 7 days, plane strain fracture toughness (KIC) was determined on an Instron testing machine at a 0.5-mm min-1 displacement rate. The glass transition temperature (Tg) in degrees C was determined after 7 days (dry and wet) storage by thermomechanical analysis. The results of this study showed significantly improved fracture toughness and lowered water sorption with the modified resin systems which was indicated by higher wet glass transition temperatures.