Evaluation of the effect of different irrigation solutions and activation systems on enterococcus faecalis biofilm in simulated lateral canals

Altunhan, A. (2024). Evaluation of the effects of different irrigation solutions and activation systems on Enterococcus faecalis biofilm in simulated lateral canals. Yeditepe University Institue of Health Sciences, Department of Endodontics. PhD Thesis. Istanbul. The aim of this study is to compare the effectiveness of four different irrigation solutions (2.5% NaOCl, 5.25% NaOCl, 2% CHX, 1% Peracetic Acid) and activation methods (Conventional Syringe Irrigation, Irriflex, EDDY, Passive Ultrasonic Irrigation) on Enterococcus Faecalis biofilms in simulated lateral canals. Transparent artificial root canals used in this study. The models were divided into 16 experimental groups (n=10) and a control group (n=10). Each irrigation solution group were activated with Conventional Syringe Irrigation, Irriflex, sonic and ultrasonic methods. Root canal models (n = 173) were manufactured from transparent resin materials using 3D printing. Each canal was created with an 18 mm length, apical size 30, a .06 taper and a lateral canal of 3 mm length, with 0.3 mm diameter. Biofilms were grown in the lateral canal and apical 3 mm of the main canal for 7 days. Three models were examined to confirm that there was E. faecalis biofilm using SEM (Scaning electron microscope). The remaining 170 models were divided into 17 groups with 10 samples in each group. In order to use only one irrigation solution in each activation group, in the groups activated with EDDY and passive ultrasonic tips, 9 ml of 2.5% NaOCl, 5.25% NaOCl, 2% CHX and 1% Peracetic Acid were irrigated for 60 seconds using a 10 ml syringe and a closed side-perforated needle, then left in the canal at rest and activated for 30 seconds with EDDY and passive ultrasonic tips. In the Irriflex and Conventional Syringe Irrigation groups, activation was performed with a 3-5 mm reciprocating motion while 9 ml of irrigation solution was delivered using a closed side-perforated needle attached to a 10 ml syringe in the root canal system. Model's apical parts were stained using the LIVE/DEAD Baclight Vitality kit, then the samples were visualized with CLSM (Confocal laser scannng microscope). The volume of living and dead bacteria was evaluated using Image J software. Anova test and Kruskal Walls H test were used for statistical analysis. The maximum volume of dead bacteria in the control group was significantly lower than in all experimental groups. The dead bacteria values in the group "2% CHX+Eddy" are significantly higher than in the groups "5.25% NaOCl+Irriflex", "5,25% NaOCl+CSI", "1% Peracetic Acid+CSI ", " 1% Peracetic Acid+Eddy", "1% Peracetic Acid+Ultrasonic", "1% Perasetic Acid+Irriflex", "2.5% NaOCl+Ultrasonic", "2.5% NaOCl+Irriflex" and 2.5% NaOCl+CSI. The dead bacteria values in the group "2% CHX+Ultrasonic" are significantly higher than in the groups "1% Peracetic Acid+CSI", "1% Perasetic Acid+ultrasonic", "1% Perasetic Acid+Irriflex", "1% Perasetic Acid+Eddy", "2.5% NaOCl+CSI" and 5.25% NaOCl+CSI. When we look at the results of our study, although a statistically significant E. faecalis decrease was observed in all groups except the positive control group in which we did not use irrigation solution, E. feacalis could not be eliminated 100% in any group. The activation of CHX resulted in better penetration of the irrigant into the lateral canals. Ultrasonic and sonic activation of CHX improved the removal of biofilm. This indicated that the irrigation protocols used should be developed further and further research should be done.