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RESEARCH PRODUCT

Effect of electric currents on antibacterial effect of chlorhexidine against Entrococcus faecalis biofilm : An in vitro study

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Background This in vitro study was mainly aimed to evaluate the effect of high-frequency alternating currents (AC) applied by an electronic apex locator (EAL) on the antibacterial properties of chlorhexidine (CHX) on E. faecalis biofilm. Material and Methods The root canals of 120 extracted human single-rooted teeth were prepared using Gates-Glidden drills and hand K-files. After contaminating the root canals with E. faecalis, they were incubated for 60 days. Then, the teeth were randomly divided into six experimental groups (n=20). Group 1, 2% CHX; group 2, normal saline (NS) with direct current (DC); group 3, normal saline (NS) with high-frequency alternating current (AC); group 4, 2% CHX with DC; group 5, 2% CHX with AC; group 6, control (normal saline). The samples were collected from the root canal walls of 16 teeth in each group and 1:10 serial dilutions were prepared and added to Muller-Hinton agar (MHA) plates and incubated at 37°C for 48 h. The longitudinal sections of the other 4 teeth used to observe under a scanning electron microscope (SEM). A classic colony counting technique was used for counting the vital E. faecalis bacteria in MHA. Two-way ANOVA was used for statistical analysis of the data. The level of significance was set at P<0.05. Results The electric current significantly changed the colony-forming units (CFU) values (P<0.001). According to pair-wise comparisons, the highest CFU difference was observed between the AC group and the group without electric current (P<0.001); furthermore, the difference between the DC group and the group without electric current was not significant (P=0.823). Conclusions The highest bioelectric effect occurred with the use of high-frequency alternating electric current in the form of an apex locator with CHX as a canal irrigant. Key words:Biofilm, Chlorhexidine, Direct current, Electric current, Enterococcus faecalis.