Effects of liquid- and paste-type EDTA on smear-layer removal during rotary root-canal instrumentation

Background/purpose: EDTA is routinely recommended as a chemical irrigant during root-canal treatment, but few studies have compared the effectiveness in smear-layer removal during rotary root-canal instrumentation. The purpose of this study was to evaluate, in vitro, the effect of liquid- and paste-type EDTA in root-canal debris removal during rotary root-canal instrumentation using an incremental crown-down technique. Materials and methods: One hundred human single-root teeth were used in this study. Specimens were accessed and instrumented with K3 rotary nickel titanium files using an incremental crown-down technique. The teeth were then randomly divided into 5 groups and alternately irrigated with 5 mL of 2.6% NaOCl and treated with one of the following chelators: Endo-cleanse, RC-Prep, Glyde-File, or File-Eze. The teeth were then dried, split into 2 halves and examined under scanning electron microscopy. The micrographs were analyzed using a 4-point evaluation index at the coronal, middle, and apical third of the root-canal wall. Results: We found that root-canal cleanliness gradually increased from the apical to the coronal part. Rates of complete cleansing were up to 48.3%. No complete root-canal cleanliness was obtained even when liquid EDTA (Endo-Cleanse) was used as the positive control. In the coronal and middle parts of the root canals, the cleaning abilities of File-Eze and Glyde-File were statistically significant better than that of RC-Prep. No differences were found in the cleansing effects in the apical part of the root canal. However, statistically significant differences were found between File-Eze and Endo-Cleanse in the coronal and apical parts of the root canals. Conclusions: The use of paste/gel-type chelators during rotary nickel titanium instrumentation resulted in improved cleanliness in the coronal and middle parts of the root canal. We recommend using liquid EDTA as a final flushing solution during root-canal preparation because it provides a better smear layer-free condition before 3-dimensional root-canal obturation. Copyright (C) 2011, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.