Background: The main objective of the biomechanical instrumentation is to completely eliminate the infected pulp tissue from the root canals. In addition to the pulpal remnants, debris and smear layer produced as a result of instrumentation must be totally removed. The efficiency of cleaning and preparation of the canals depends on several factors likedesign of the file, sequence of file usage, rotational speed, and surface conditioning of the instruments. Aim: The aim of this study is a comparative evaluation of cleaning efficacy of Hyflex [coltinewaldent] rotary files, Hero shaper [Micro-Mega, Besançon, France] Rotary files, using a Scanning Electron Microscope. Material and method: A total of 50 extracted maxillary permanent central incisors were taken, divided into two equal groups. Of these two groups, one group is instrumented with Hyflex [coltinewaldent] rotary files and another group is instrumented with Hero shaper [Micro- Mega, Besançon, France] files. After the completion of preparation, the crown portion was removed and roots were split into two halves longitudinally and prepared for scanning electron microscope study. Both of the groups were divided into three areas namely coronal, middle and apical third and are examined under Scanning Electron Microscope. Results: The results of the study illustrates completely clean root canal walls were not observed in either of the instrumentation group. However the group instrumented with Hyflex files has less scores of debris and smear layer in coronal and middle third of root canals when compared to the ones that are instrumented with Hero shaper files. On the other hand, the group of extracted teeth instrumented with Hero shaper files has less debris and smear layer scores in the apical third of canals than the Hyflex files. Conclusion: Under the circumstances of this study, both Hyflex and Hero shaper files can be recommended for clinical practice. Both the Hyflex and Hero shaper files showed clear or less debris and smear layer in the coronal and middle third but unable to produce the much clear surface in apical third.
