Abstract : The success of endodontic treatment is dependent on triad endodontic. The endodontic instrument has tendency to leave amount of smear layer after its use. Therefore, irrigation becomes fundamental to ensure the cleaning. The goal of this research is to observe the differences among files toward smear layer production and the most effective activation method. Twenty-four single canal mandible premolars were decoronated in the cementoenamel junction and root canal treatment followed. The teeth were divided into four groups: Group A (sample was prepared using F-One Blue and activated using sonic frequency (EDDY)), Group B (sample was prepared using F-One Blue and activated using subsonic frequency (EndoActivator)), Group C (sample was prepared using TruNatomy and activated using sonic frequency (EDDY)) and Group D (sample was prepared using TruNatomy and activated using subsonic frequency (EndoActivator)). All teeth were cut longitudinally then examined using Scanning Electron Microscope (SEM). SEM results were scored using double blind method. One-way ANOVA test showed there were differences in the removal of smear layer. Post Hoc LSD test showed there was significance difference between group B and group D; also between group D and group A. The other groups showed no difference statistically. It was concluded that all preparation and activation methods will leave the smear layer in root canal system whatsoever. Preparation of root canal using F-One Blue file, irrigated using 2,5% NaOCl and activated using sonic frequency (EDDY) showed the best smear layer removal. Study on activation method showed no significance differences between EDDY nor Endoactivator.