Exploring the Impact of Various Irrigation Protocols on Endodontic Biofilms Cultivated on Prototyped Root Canals

Introduction : This study used a new in-vitro model to assess the antimicrobial effectiveness of various irrigation protocols: positive pressure (PP), ultrasonic activation (UA), Er: YAG laser activation (PIPS), and high-frequency conduction (HFC) therapy. Methods: Resin-prototyped root canals were created using tomographic images of the distal root of a lower molar, which were then converted into STL files for 3D printing. Biofilms of nine bacterial species were cultivated on the prototyped root canals for 60 days. The biofilms were treated with 2.5% NaOCl, followed by 17% EDTA, and final irrigation with 2.5% NaOCl. The activation protocols tested included UA, PIPS, and HFC, while the PP group represented the non-activated protocol. Biofilm cells were suspended after treatment, and the total colony-forming units (CFU) were quantified. The CFU data were log-transformed and analyzed using ANOVA and the Tukey tests (p < .05). Results: The HFC and PIPS groups exhibited the lowest bacteria levels, with no significant difference between them (p > .05). The UA group showed lower bacterial levels compared to the PP group (p < .05) but higher bacterial levels compared to the PIPS group (p < .05). Conclusions: The irrigation protocols significantly impacted the removal of complex biofilms from the prototyped root canals. The most effective methods for reducing bacterial load were high-frequency conduction therapy and PIPS activation.