Abstract
The aim of this study was to evaluate the effect of irrigation regimens on dentin microhardness at the furcation area of mandibular molars, using sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA), individually and in alternation. The occlusal surface and the roots of 20 non-carious extracted human permanent mandibular molars were cut transversally and discarded. The tooth blocks were embedded in acrylic resin and randomly assigned to 4 groups (n=5) according to the irrigating regimens: 1% NaOCl solution, 17% EDTA solution, 1% NaOCl and 17% EDTA and distilled water (control). Knoop microhardness of dentin at the furcation area was evaluated. Data were analyzed using one-way ANOVA and Tukey's multiple comparison tests (α=0.05). The results of this study indicated that all irrigation solutions, except for distilled water (control), decreased dentin microhardness. EDTA did not show a significant difference with NaOCl/EDTA (p>0.05), but showed a significant difference with NaOCl (p<0.01). EDTA and NaOCl/EDTA showed a maximum decrease in microhardness. The 17% EDTA solution, either alone or in combination with 1% NaOCl reduced significantly dentin microhardness at the furcation area of mandibular molars.
Highlights
The smear layer produced by files and drills during root canal instrumentation is a film of debris attached to dentin surface, composed by excised dentin particles, remnants of vital or necrotic pulp tissue, microorganisms and their byproducts, and retained chemical irrigants [1]
A recognizably efficient protocol for removal of smear layer is the use of sodium hypochlorite (NaOCl) in concentrations ranging from 0.5% to 6.15% and 17% ethylenediaminetetraacetic acid (EDTA) as initial and final irrigating solutions, respectively [5]
The aim of this study was to evaluate the effect of irrigation regimens on dentin microhardness at the furcation area of mandibular molars, using 1% NaOCl and 17% EDTA, individually and in alternation
Summary
The smear layer produced by files and drills during root canal instrumentation is a film of debris attached to dentin surface, composed by excised dentin particles, remnants of vital or necrotic pulp tissue, microorganisms and their byproducts, and retained chemical irrigants [1]. The smear layer has a negative impact on root canal adhesion because it will act as a physical barrier between the filling material and canal walls, undermining sealer penetration and formation of intratubular tags [2]. Several chemical agents are available with different properties, as far as cleaning of root canals is concerned, no currently available endodontic irrigant fulfills all ideal physicochemical properties to act simultaneously on the organic and inorganic components of smear layer [4]. A recognizably efficient protocol for removal of smear layer is the use of sodium hypochlorite (NaOCl) in concentrations ranging from 0.5% to 6.15% and 17% ethylenediaminetetraacetic acid (EDTA) as initial and final irrigating solutions, respectively [5]
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