Effect of liquid rubber additions on physical properties of Bis-GMA based dental resins

Objective m of this investigation was to determine the effect of an experimental liquid rubber (LR) toughening agent on fracture toughness, crosslink density and Barcol hardness of polymerized mixtures of 50/50 wt% Bis-GMA and TEGDMA. s erimental LR, was added to a solution of Bis-GMA and TEGDMA containing 1 wt% dimethylamino ethyl methacrylate and 0.5 wt% camphoroquinone at concentrations 0–10%. The composites were polymerized by exposure to a visible light curing unit for 60 s. Fracture toughness was determined according to ASTM. 399. Crosslink density was evaluated using a swell test in ethanol. s racture toughness values ranged from 0.39 MPa m1/2 for samples containing 6% to 1.24 MPa m1/2 for samples containing 8% LR. Fracture toughness of samples containing 2%, 4%, and 8% LR were significantly higher than controls. The highest degree of cross-linkage was obtained in controls and lowest for samples containing 2% LR. Barcol Hardness values ranged from 36.7 for the control and 4% LR composition to 31.2 for samples containing 10% LR. icance on of 2, 4 and 8% LR increases the fracture toughness of Bis-GMA/TEGDMA composites. Addition of LR shows promise as a method of improving the fracture toughness of Bis-GMA based dental composites.