Effect of ethylenediaminetetraacetic, etidronic, and peracetic acids with different concentrations on the removal of Enterococcus faecalis biofilms from root canal walls: an in vitro study

Abstract Background To evaluate the effects of 17% ethylenediaminetetraacetic acid (EDTA), 9% and 18% etidronic acid (HEBP), and 1% and 2% peracetic acid (PAA) used alone or in combination with NaOCl on Enterococcus faecalis biofilms by using laser scanning confocal microscope. Methods E. faecalis biofilms were experimentally developed on the dentine discs obtained from one hundred and fifteen teeth. Infected dentine discs were randomly divided into 11 experimental (n = 10) and one control group (n = 5) according to the irrigation regimen. The percentage of dead cells in the infected samples after exposure to the different irrigation solutions was measured using a confocal laser scanning microscope. The data was statistically analyzed using the Saphiro-Wilk test and Tukey multiple comparison test with one-way ANOVA. A p-value less than 0.05 was considered to be statistically significant. Results The percentage of dead bacterial cells in the samples irrigated using 17% EDTA and saline was significantly lower compared to the samples irrigated with other irrigation regimens (p < 0.001). The percentage of dead bacteria observed in the samples irrigated using 9% HEBP and 18% HEBP solutions alone is lower compared to the samples irrigated using HEBP in combination with NaOCl (p < 0.001). There was no statistically significant difference between the two concentrations of peracetic acid (1–2%) and etidronic acid (9–18%) regarding biofilm elimination when these chelators were used alone or in combination with NaOCl (p > 0.001). The use of 2% peracetic acid alone in the experimentally infected samples resulted in more biofilm elimination than the use of 9% and 18% HEBP alone (p < 0.001). Conclusion The antimicrobial capacity of 1–2% peracetic acid is similar to its associated use with 2.5% NaOCl regarding eliminating E.faecalis biofilms from root canal walls. Therefore, irrigation of infected root canals with a single use of PAA can achieve an adequate antibacterial effect. Lower concentrations of peracetic acid and etidronic acid can be recommended to remove the E.faecalis biofilms from root canals to decrease the irrigation solutions' potential harmful effects.