Abstract
The aim of this study was to compare the efficiency of four final irrigation protocols in smear layer removal and bacterial inhibition in root canal systems. Thirty roots inoculated with Enterococcus faecalis were prepared with ProTaper Universal files. The teeth were disinfected by conventional needle irrigation, sonic agitation using the EndoActivator device, passive ultrasonic irrigation, or an M3 Max file. Teeth with no root canal preparation served as blank controls for the establishment of the infection baseline. Teeth with preparation but no final irrigation served as a post-instrumentation baseline. After the final irrigation, the teeth were sectioned in half. One half of each tooth was examined by scanning electron microscopy (SEM) to assess smear layer removal using a five-point scale. The other half was examined by confocal laser scanning microscopy (CLSM) using the LIVE/DEAD BackLight bacterial viability kit to evaluate the depth of bacterial survival in dentinal tubules. SEM analysis revealed no significant difference in smear layer removal throughout the whole canal among the EA, PUI, and M3 Max groups (P > 0.05). CLSM revealed that PUI achieved the greatest bacterial inhibition depth in the coronal ((174.27 ± 31.63) μm), middle ((160.94 ± 37.77) μm), and apical ((119.53 ± 28.49) μm) thirds of the canal (all P < 0.05 vs. other groups). According to this comprehensive SEM and CLSM evaluation, PUI appears to have the best infection control ability in root canal systems.
Highlights
The main goal of endodontic treatment is to maintain or promote periapical tissue healing.[1]
This study compared the efficacy of four irrigation protocols in terms of smear layer removal and lateral penetration into the dentinal tubules to kill bacteria
Combined scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) analysis of the same root canal systems allowed us to demonstrate the relationship between smear layer removal from the canal wall surfaces and the bactericidal effect deep in the dentinal tubules
Summary
The main goal of endodontic treatment is to maintain or promote periapical tissue healing.[1] In infectious root canals, chemomechanical cleaning and shaping of the root canal system to eliminate or reduce bacterial populations are key for positive endodontic outcomes.[1,2] the creation of completely sterile conditions is challenging. Mechanical preparation cannot reach large areas (>35%) of the canal walls, in the apical third of the root.[3,4] chemical irrigation is of great importance for root canal disinfection. Sodium hypochlorite (NaOCl) is the most popular and widely used chemical irrigant due to its efficacy against pathogenic organisms and pulp digestion.[5,6]
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