The evaluation of dentin microhardness after use of 17% EDTA, 17% EGTA, 10% citric acid, MTAD used as chelating agents combined with 2.5% sodium hypochlorite after rotary instrumentation: An in vitro SEM study

Abstract

Introduction: The smear layer removed during root canal instrumentation enables penetration of irrigant solution and adhesion of root canal sealants providing a fluid tight seal of obturated root canals, necessitating its removal. The aim of the study was to compare the effect of smear layer removal by 17% Ethylene diamine tetraacetic acid (EDTA), 17% Ethylene glycol tetraacetic acid (EGTA),10% Citric acid and (MTAD solution) a Mixture of tetracycline isomer, an acid and a detergent applied as final rinse , when used along with 2.5% (NaOCl) Sodium hypochlorite and its effect on dentin microhardness. Materials and Methods: Sixty single-rooted human mandibular premolars with minimum curvature (<5°) were instrumented using rotary instrumentation till apical enlargement size 35 RaCe file 0.04 taper. During instrumentation, the canals were irrigated with 2-mL 2.5% NaOCl. After instrumentation, teeth were rinsed with distilled water and were divided into 5 groups (n = 12) according to final rinse for 1min with 5-mL 17% EDTA followed by 5-mL 2.5% NaOCl (group 1, control group), 17% EGTA (group 2), MTAD solution (group 3), 10% citric acid (group 4), and 17% EDTA (group 5). Teeth were split through the groove prepared, and one-half of specimen were evaluated for smear layer removal using scanning electron microscopy. A score system was followed to evaluate the images and comparisons among groups were performed using Kruskal–Wallis one-way analysis. Multiple comparisons were performed using Mann–Whitney U test. The other half was evaluated for dentin microhardness using Vickers microhardness testing machine. Microhardness values were statistically analyzed using parametric one-way analysis of variance test. Conclusion: Irrigation regimen following the use of 2.5% NaOCl during instrumentation followed by application of 5-mL 17% EDTA solution for 1min resulted in efficient smear layer removal and less decrease in dentin microhardness compared with 17% EGTA, 10% citric acid, and MTAD solution.

Keywords

• Chelating solutions
• dentin erosion
• dentin microhardness
• smear layer