Research Information System
Archives of Oral Biology, vol.187, 2026 (SCI-Expanded, Scopus)
Objectives: This study compared the antibacterial efficacy of sodium hypochlorite (NaOCl) and a NaOCl–1-hydroxyethane-1,1-diphosphonic acid (NaOCl/HEDP) mixture at 25°C and 37°C, with or without passive ultrasonic irrigation (PUI), in an internal root resorption (IRR) model infected with Enterococcus faecalis biofilm. Design: Standardized IRR cavities were prepared in extracted maxillary incisors. After 21-day biofilm maturation, specimens were allocated to eight subgroups (NaOCl or NaOCl/HEDP; 25°C or 37°C; conventional needle irrigation [CNI] or PUI; n = 8 each) and a saline control (n = 8). Antibacterial activity was assessed by colony-forming unit (CFU) reduction, and biofilm morphology was evaluated via scanning electron microscopy (SEM). Data were analyzed using factorial ANOVA (irrigant type×temperature×activation), with partial η² and Cohen's f reported (α=0.05). Results: All experimental groups showed significant bacterial reduction compared with the control (P < 0.001). Significant main effects were observed for temperature (F=89.7, P < 0.001, η²=0.62), activation (F=50.6, P < 0.001, η²=0.48), and irrigant type (F=19.8, P < 0.001, η²=0.26). Temperature had a stronger enhancing effect in the NaOCl/HEDP groups. The greatest reduction occurred with NaOCl/HEDP at 37°C combined with PUI. SEM images confirmed cleaner dentine surfaces and reduced debris in the 37°C and PUI groups, particularly with NaOCl/HEDP. Conclusions: Both temperature elevation and PUI improved antibacterial efficacy, and NaOCl/HEDP demonstrated the strongest temperature-dependent response. Their combined use resulted in the highest bacterial reduction, although complete bacterial removal was not achieved.