Fracture resistance testing

Specimens from all groups were prepared for test assembly. The apical 5 mm of roots were embedded along the long axis in self-curing acrylic blocks with 8 mm of each root exposed. Fracture resistance of the specimen was tested using a Universal Testing Machine (Lloyd, LR50K, UK). A custom made stainless steel loading indenter with a round tip (r = 2 mm) was used to deliver force directed along the long axis of the tooth. The load increased at the rate of 1 mm/min until fracture occurred. The fracture was evidenced by an audible crack and/or a sudden drop in load as seen on the graph. The force necessary to fracture each root was recorded in Newtons (N). The peak load to fracture the samples was recorded.