OR05 - SEM Study on the Effect of 6% Sodium Hypochlorite, 17% Ethylenediamine Tetraacetic Acid, and Triton All-in-One on Smear Layer Removal, Dentin Erosion and Microhardness

Abstract:
Cleaning and shaping root canals produces a smear layer that could harbor dentinal particles and remnants. Removing the smear layer has been advocated to allow better irrigation penetration into dentinal tubules. Nevertheless, dentin erosion could occur when sodium hypochlorite and EDTA were alternately applied. Thus, this study aims to determine the effect of 6% NaOCl, 17% EDTA, and Triton all-in-one on smear layer removal, root canal dentin microhardness, and erosion scores with different irrigation protocols. Forty single-rooted teeth were decoronated at the CEJ and randomly divided into four groups (n=10) according to the irrigation solutions used: Saline (S), 6% NaOCl/17% EDTA/6% NaOCl (NEN), 6% NaOCl/17% EDTA/Saline (NES), and Triton all-in-one (TO). All experimental roots were instrumented with WaveOne Primary rotary files. Dentinal microhardness was measured with a Knoop indenter at 500 µm from the center of the lumen before and after instrumentation and irrigation. The roots were sectioned longitudinally and prepared for scanning electron microscopic analysis. The amount of dentin erosion and smear layer at mid-root and apical root sections were examined. Preliminary results demonstrated that more extensive erosion in dentinal tubules was observed at the mid-root section for the NEN group, followed by NES and TO groups. There appeared to be no significant differences in the reduction of microhardness among all protocols. Although Triton all-in-one did not cause extensive dentinal tubule erosion, it appeared to be less effective in removing the smear layer when compared with NEN and NES at the mid-root level.