Highlights
- •We formed biofilms in teeth with large root canals and unlimited irrigant access.
- •The effect of mechanical instrumentation (MI) and noninvasive irrigating protocols on bacteria was compared.
- •MI was the most effective and reliable method to disinfect large root canals.
- •Passive ultrasonic irrigation (PUI) enhanced the efficacy of sodium hypochlorite irrigation.
- •Noninvasive disinfection protocols, including PUI, could not substitute for MI.
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 to verify
biofilm formation. The remaining specimens were assigned into 5 experimental groups
and a sterile control group: mechanical instrumentation using files size 60–90 and
2.5% sodium hypochlorite (NaOCl) (MI-N), irrigation with 2.5% NaOCl (IR-N), irrigation
with 2.5% NaOCl using intermittent passive ultrasonic irrigation (PUI-N), irrigation
with normal saline, and no intervention (initial). After root canal disinfection,
dentin specimens were collected for microbial analysis. Mean colony forming units
were determined and compared between groups using 1-way analysis of variance.
Results
The lowest number of intracanal bacteria (24.5 colony-forming units/mL) was recovered
from the MI-N group followed by the PUI-N and IR-N groups. The irrigation with normal
saline group did not show a significant reduction compared with the initial group.
However, there were significant differences between groups (P < .01). The remaining bacteria in the PUI-N group was 4.5-fold lower compared with
the IR-N group; however, it was 1862-fold higher compared with the MI-N group.
Conclusions
MI-N was the most effective method to disinfect large root canals. Although ultrasonic
activation enhanced the efficacy of root canal irrigation, it could not substitute
for mechanical instrumentation even in large root canals with unlimited irrigant access
to the apical portion.
Key Words
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Article info
Publication history
Published online: January 29, 2016
Identification
Copyright
© 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
