Evaluation of two endodontic irrigation needles on curved root canal disinfection: an ex vivo study

Aim: The study aimed to compare the effectiveness of two different irrigation needles in eliminating E. faecalis from contaminated curved root canals and to test their difference in flexibility. Materials and methods: Thirty-five extracted multirooted teeth with visible curved canals were instrumented, autoclaved at 121 °C for 25 minutes, and contaminated with 10 μL of the bacterial suspension. The teeth were randomly divided into three groups: A (IrriFlex), B (Navitip), and C (Control). After an incubation period of 21 days at 37 °C, group C was irrigated with 20 μL of sterile saline solution. Groups A and B were irrigated with 5 ml of 5% sodium hypochlorite (NaOCl) solution by inserting the respective needle tip until the apical third, neutralized with 5 mL of 5% sodium thiosulfate and rinsed with 5 mL of sterile saline. Three sterile paper points for each sample were taken, transferred into a brain heart infusion (BHI) medium under aseptic conditions, and frosted immediately at -20 °C. Colony-forming unit (CFU) counting was assessed after microbiological culture on selective media for E. faecalis. A customized device was used to test the bending behavior of the tips at 3 mm, 6 mm, and 9 mm. Kruskal-Wallis and Dunn tests were used for statistical analysis. Results: IrriFlex needle demonstrated higher flexibility with no statistical difference at 3 and 6 mm compared to NaviTip. NaOCl irrigation with NaviTip Tip and IrriFlex effectively reduced E. faecalis CFU count. Conclusions: NaOCl irrigation with NaviTip Tip and IrriFlex demonstrated high and comparable efficacy in removing E faecalis from curved canals of multirooted teeth.