An in vitro evaluation of biofilm removal from simulated root canals using sodium hypochlorite irrigation solution at various temperature settings

Objectives: Using NaOCl irrigation solution at various temperatures is common for removing biofilms in root canals and isthmus. While numerous studies have examined the impact of temperature on biofilm removal in extracted teeth, there needs to be more research on 3D-printed artificial teeth. Therefore, this study aimed to assess the effect of needle irrigation using NaOCl irrigation solution heated at different temperatures on the structure of E. faecalis biofilm on artificial teeth produced via 3D printing technology. Materials and Methods The isthmus in the mesial canals of 55 artificial tooth samples produced using 3D printing technology from the 3D model obtained by micro-CT analysis of the lower first molar tooth was evaluated. Standard strain E. faecalis ATCC 19433 was used to infect artificial tooth specimens. The samples were divided into a negative control group and four experimental groups receiving sodium hypochlorite solutions at 21°C, 45°C, 60°C, and 150°C. Following irrigation, SEM imaging was conducted at varying magnifications to visualize remaining biofilm areas in root canals and isthmus. The ImageJ program quantified biofilm areas in the isthmus region, and statistical analyses, including Shapiro-Wilks, Kruskal Wallis H, and t-tests, were performed on the measurements. Results The results did not differ between the control and 21°C groups (P > 0.05). However, removal areas were larger in the 45, 60 and 150°C groups than in the control group (p ≤ 0.05). No difference was observed in the biofilm removal efficiency in different isthmus regions (P > 0.05). Conclusions Findings revealed that an increase in temperature increased the removal areas. Clinical Relevance: The temperature of the irrigation solution could be as high as possible to obtain optimum removal of the biofilms.