The purpose of this study was to evaluate the effects of EDTA on smear layer removal and on the structure of dentin, after 1 and 10 min of application. Six extracted single-rooted teeth were instrumented to #60. Apical and coronal thirds of each root were removed, leaving a 5 mm middle third that was then cut longitudinally into two equal segments. Using 10 ml of 17% EDTA solution, halves belonging to the same root were irrigated for 1 and 10 min, respectively. All specimens were subjected to irrigation with 10 ml of 5% NaOCl. Then all the specimens were prepared for SEM evaluation. The results showed that 1 min EDTA irrigation is effective in removing the smear layer. However a 10-min application of EDTA caused excessive peritubular and intertubular dentinal erosion. Therefore we suggest that this procedure should not be prolonged >1 min during endodontic treatment.

No abstract

The purpose of this study was to compare the effects of ethylene glycol-bis (beta-aminoethyl ether)-N,N,N', N'-tetraacetic acid (EGTA) and EDTA on removal of the smear layer by using scanning electron microscopy. Fifteen single-rooted teeth were instrumented to size 60. Three teeth served as the control group, and the remaining teeth were assigned into two groups. After instrumentation, root canals of the first group were irrigated with 10 ml of 17% EDTA, and the second group was irrigated with 10 ml of 17% EGTA for 2 min. Both were then irrigated with 10 ml of 5% NaOCl. The teeth in the control group were irrigated with only 10 ml of 5% NaOCl. Then the specimens were sectioned longitudinally and processed for scanning electron microscopy. The results showed that the smear layer was completely removed by EDTA, but it caused erosion of the tubuli. EGTA was somewhat effective in removing the smear layer without inducing erosion. Our results suggest that EGTA is an alternative chelator for removing the smear layer.

The purpose of this study was to compare the effects of concentration and pH variations of EDTA on dentin demineralization. Twenty extracted, human permanent teeth with single canals were used in this study. Demineralizing effects of EDTA solutions at 10% and 17% concentrations at pH 7.5 and 9.0 were determined by measuring the amount of liberated phosphorus 1, 3, 5,10, and 15 min after exposure. The results showed that the amount of phosphorus liberated from dentin was greater with increased EDTA concentration and increased time of exposure, and it was more effective at neutral pH than pH 9.0. The pH of the EDTA solutions did not display any significant alterations during the demineralization process.

Use of chelating agents alone or in combination with NaOCl decreased the wettability of root canal wall dentine.