Effectiveness of Sodium Hypochlorite plus EDTA Compared with Peracetic Acid in Removing Smear Layer and Killing .

Introduction: The aim of this study was to evaluate the effectiveness of 2.5% sodium hypochlorite associated with 17% Ethylenediaminetetraacetic acid (NaOCl-EDTA), that of 1% peracetic acid (PA), in removing the smear layer, as assessed by scanning electron microscopy (SEM), and in exerting bactericidal action against ( as assessed by the real-time polymerase chain reaction (real-time PCR).

Methods And Materials: Fifty-five extracted mandibular single-rooted premolars were selected, and divided into two experimental groups (NaOCl-EDTA and PA; =25) and one control group (0.9% saline; =5). Pre- and post-instrumentation samples were collected and assessed for the presence of using real-time PCR. The teeth were instrumented using hand files and the ProTaper Universal system (hybrid technique) for a standardized time of 7 min. A total of 20 mL of NaOCl followed by 5 mL of EDTA were applied during instrumentation in the NaOCl-EDTA group, whereas 20 mL of PA and 20 mL of saline were applied in the PA and control groups, respectively. An additional 5 mL of saline was applied in all the groups to neutralize the environment. A scoring system was used to conduct the SEM assessment. The results were submitted to the Kruskal-Wallis test, complemented by Dunn's test (SEM analysis) (<0.05).

Results: A significant microbial reduction was observed in both the PA and the NaOCl-EDTA groups (<0.05). In the PA group, the presence of a smear layer in the apical third was significantly greater than in the cervical third (<0.05); no significant differences were observed between the middle and cervical thirds, or between the middle and apical thirds (>0.05). In the NaOCl-EDTA group, the smear layer scores were significantly higher in the apical third than in the cervical and middle thirds (<0.05).

Conclusion: This study showed that there was no significant difference between PA and NaOCl-EDTA irrigation regimens regarding either antimicrobial action against or removal of the smear layer, except for greater removal in the middle third by the NaOCl-EDTA group.