Abstract
To evaluate the antimicrobial, toxicity and cleaning effectiveness of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) alone and combined with cetrimide (CTR). Cytotoxic and genotoxic effects were assessed on Chinese hamster cells V79 using the MTT, clonogenic and micronucleus assays, respectively. The bacterial inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined on a strain of Enterococcus faecalis. Antimicrobial tests were performed on a biofilm model after treatment with the chelating agents by using a biofilm eradication concentration (MBEC) and confocal laser scanning microscope (CLSM) assays. Quantification of cell biomass and percentage of live and dead cells in the biomass were assessed for each group. The percentage reduction of accumulated hard-tissue debris (AHTD) after root canal preparation and final irrigation protocols was evaluated by micro-CT. Statistical tests of one-way analysis of variance (anova), Bonferroni test, Kruskal-Wallis test, Dunn's multiple comparison test and Wilcoxon matched-pairs signed-rank tests were used. Cetrimide alone as well as in combination with EDTA and MA at dilutions of 1/10 and 1/100 was significantly more toxic as compared to untreated controls (P<0.001). All tested mixtures were nontoxic at a dilution of 1/1000. EDTA retained a weak inhibitory and bactericidal effect against planktonic cells, whilst MA inhibited cells growth and killed 99.9% of the cells when diluted. CTR revealed the most prominent effect, being inhibitory and bactericidal, also when diluted. Cetrimide alone or combined with EDTA was able to remove, respectively, 40% (P<0.01) and 60% (P<0.001) of the entire biomass after 1min. Conversely, MA alone and in combination with CTR did not have a significant effect on biomass reduction. After final irrigation, the AHTD volume was significantly decreased in all groups (P<0.05). EDTA+CTR and MA+CTR were associated with a significant reduction in the percentage of AHTD on the entire root canal compared to the same solutions without surfactant. 7% MA was less cytotoxic in comparison with 17% EDTA. The addition of cetrimide to EDTA and MA removed accumulated hard-tissue debris effectively from the canal walls and increased their antimicrobial activity when compared to the same solutions without detergents.
Highlights
The main goal of root canal treatment is to optimize root canal disinfection and to prevent re-infection of the root canal space after treatment (Zehnder 2006)
Mechanical instrumentation of the root canal system produces an irregular, granular layer covering the canal walls known as the smear layer (McComb & Smith 1975), which consists of inorganic dentine debris, pulp tissues, severed odontoblastic processes, necrotic debris, microorganisms and their metabolic products (Torabinejad et al 2002)
The accumulated hard-tissue debris (AHTD) volume was significantly decreased in all groups (P < 0.01)
Summary
The main goal of root canal treatment is to optimize root canal disinfection and to prevent re-infection of the root canal space after treatment (Zehnder 2006). Cleaning and shaping of the root canal system are considered the key requirements in eliminating microorganisms. Studies have demonstrated that removal of smear layer improves the fluid-tight seal of filled root canals, allows the elimination of bacteria within the dentinal tubules and facilitates the penetration of intracanal medicaments, irrigating agents and sealers into the dentinal tubules, increases the bond strength of resin sealers to root canal dentine, resulting in a significantly better apical seal (White et al 1984, Cergneux et al 1987, Ørstavik & Haaapasalo 1990, Gettleman et al 1991, Shahravan et al 2007). Combined application of ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) is frequently recommended for effective removal of the smear layer from the root canal system (Zehnder et al 2005). Irrigating agents intended for endodontic use should be biocompatible when applied as intended (Peters 2013)
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