Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to evaluate and compare the debridement efficacy of the EndoActivator (Dentsply Tulsa Dental, Tulsa, OK) versus the Ultrasonic Bypass system (Vista Dental) following hand-rotary instrumentation in anterior teeth. Sixty extracted human, maxillary anterior teeth were randomly assigned to three groups. Teeth were instrumented using (ISO k-flex) hand files and EndoSequence nickel-titanium rotary files (Brasseler, Savannah, GA) to a size 40/.06 taper. Group 1 served as the control group and had no additional treatment performed. Groups 2 and 3 were subjected to a final irrigating regimen that consisted of 6-percent sodium hypochlorite for a 1- minute duration. For group 2 the irrigation solution was activated for 1 minute using the EndoActivator system (DENTSPLY). For group 3, the irrigation solution was activated for 1 minute using the Ultrasonic Bypass System (Vista Dental). The teeth were then sectioned longitudinally and each half was divided into three equal parts 3 mm from the anatomic apex. The sample with the most visibly identifiable section of the apex was used for SEM evaluation. A scoring system to measure the efficacy of debris removal was utilized to quantify the results. Statistical analysis was performed using the Kruskal- Wallis test. If the overall test is significant, a Wilcoxon Rank Sum tests was used to compare each pair of groups. The results of this study indicate that both the EndoActivator and Ultrasonic Bypass groups had a smaller percentage of canal space occupied by smear layer and debris when compared with the control group at all three levels. This difference was statistically significant for the Ultrasonic Bypass System when compared with the control at both the coronal and middle thirds of the samples evaluated. This difference was not statistically significant in the apical third. When compared with the EndoActivator, the Ultrasonic Bypass System produced cleaner canals in the coronal and middle thirds, with the difference being statistically significant in the middle third only. These results of this research support the use of either of these two devices when compared with the controls. Smear layer removal and debridement efficacy was greatly increased when using either sonic or ultrasonic activation of sodium hypochlorite. More research is warranted concerning these two devices. Examining the antimicrobial efficacy with the use of these two devices could lend additional validation to their use in non-surgical endodontic therapy.