Abstract:
Introduction: This study compared the effectiveness of different disinfection protocols in reducing bacteria in an Enterococcus faecalis biofilm in teeth with large root canals. Methods: Fifty-five roots were prepared from human mandibular premolars with large single root canals and 50 roots were infected with E. faecalis for 21 days. Four roots were observed using scanning electron microscopy (SEM) to verify biofilm formation. The remaining specimens were assigned into 5 experimental groups and sterile control group: mechanical instrumentation using files size 60–90 (MI); irrigation with 2.5% NaOCl (IRN), irrigation with 2.5% NaOCl followed by intermittent passive ultrasonic irrigation (PUI), irrigation with normal saline (IRS), and no intervention (initial). After root canal disinfection, dentin specimens were collected for microbial analysis. Mean colony forming units (CFU) counts were calculated and compared between groups using one-way ANOVA. Results: The lowest number of intracanal bacteria (24.5 CFU/mL) was recovered from the MI group followed by the PUI and IRN groups. IRS alone did not demonstrate a significant reduction compared with the initial group. However, there were significant differences between groups (P <.01). The remaining bacteria in the PUI group was 4.5 fold lower compared with the IRN group, however, it was 1862 fold higher than that in the MI group. Conclusions: MI was the most effective method to disinfect large root canals. Although PUI enhanced the efficacy of root canal irrigation, it could not substitute for MI, even in large root canals where irrigant access to the apical portion was unlimited.
