AbstractThe purpose of this study was to evaluate the effect of heat treatment on the transformation temperatures of K3, K3XF and MTwo endodontic files. DSC was used to investigate the domains of transformation temperatures and how the transformation temperatures vary along the file. The files were analysed as received and subjected to heat treatment. X-ray diffraction analysis was also used to investigate the stress-induced martensite transformation on the files under flexion. The results show that heat treatment influences the transformation temperatures and that under flexion, the conditions and situations in which files present a stress-induced martensite transformation can be identified.