Evaluation of surface topography of two different heat treated NiTi file systems used with sodium hypochlorite: A stereomicroscope and SEM study

The surface grooves on endodontic files act as stress concentration and it lowers their susceptibility to fatigue fracture. Hence, 80 first mandibular molars were prepared with 40 rotary instruments, 20 One Curve (OC; Micro-Mega) and 20 TruNatomy (TN; Dentsply Sirona,) rotary files. The files were rotated in mesial curved canals with irrigation with 5.25% sodium hypochlorite (Normal temperature and preheated) and inspected under SEM for surface roughness. Stereomicroscope analysis was done for Unwinding and Distortion. One Curve files showed signs of deformation and distortion earlier as compared to TruNatomy in curved canals. Sodium hypochlorite (Preheated form) affects the surface topography and fatigue resistance of the files.