Comparison of the smear layer- and debris-removal abilities and the effects on dentinal microhardness of 5% and 17% EDTA solutions used as final irrigants: in vitro study

Abstract

OBJECTIVE: The aim of this in vitro study was to evaluate the effects on dentinal microhardness, and the smear layer- and debris-removal properties, of 5% and 17% ethylenediaminetetraacetic acid (EDTA) solutions when used as final irrigants. MATERIALS AND METHOD: Seventy extracted single-root human mandibular premolars were endodontically instrumented and distributed into 4 groups, according to the final irrigant: G1: 17% EDTA + 2.6% NaOCl (applied for 3 min and 1 min, respectively), G2: 5% EDTA + 2.6% NaOCl, G3 (control): saline + 2.6% NaOCl, and G4 (control): saline. Teeth from G1–G3 were split longitudinally, and scanning electron micrographs were obtained at 2 and 6 mm from the apex for smear layer and debris analyses. Teeth in all groups were sectioned horizontally, and Vickers microhardness values were measured at 500, 1000, and 1500 µm from the canal lumen. Data were statistically analyzed at the p<0.05 level. RESULTS: Smear layer scores were significantly greater at the 2-mm vs the 6-mm level in both EDTA groups, with no significant difference between EDTA groups at either level. Significantly less smear layer was found in the 17% EDTA group compared to the control at the 2-mm level. A statistically significant difference in microhardness among groups was found only at the 1500-µm level, with the 17% EDTA group exhibiting the lowest microhardness values. CONCLUSION: The 5% and 17% EDTA solutions were equally effective at removing the smear layer and debris from instrumented root canal surfaces. However, the 5% EDTA solution did not decrease the microhardness of dentin like 17% EDTA.

Keywords

• Anisotropy
• chelating agents
• endodontics
• root canal irrigants
• root canal therapy