Fracture toughness determination of dental amalgams through microindentation.

A microindentation technique was used to study and estimate the fracture toughness of six amalgams. A significant difference is observed between fracture toughness at the bulk and the margin of amalgams. All amalgams show significant differences in fracture toughness as a function of distance from the margin. Microindentation measurement of fracture toughness appears to be an effective method of evaluating the localized brittleness of amalgams.