Pinheiro SR, et al. - This research was designed to assess apical transportation and centering ability during root canal preparation in mesial root canals of mandibular molars associated with ProTaper Gold (PTG), ProDesign S (PDS), Hyflex CM (HCM), Hyflex EDM (HEDM) and ProDesign Logic (PDL). The physicians concluded that all the thermally treated systems resulted in comparable apical transportation. The Hyflex CM and Prodesign Logic systems provided more centered preparations in the cervical region.