Mechanical reduction in intracanal Enterococcus faecalis when using three different single-file systems: an ex vivo...

Area of Science:

• Endodontics
• Microbiology
• Dental Materials Science

Background:

• Root canal infections, primarily by Enterococcus faecalis, pose a significant challenge in endodontic treatment.
• Effective mechanical preparation is crucial for reducing intracanal bacterial load and biofilm.
• Various single-file nickel-titanium (NiTi) rotary systems are available, each with distinct design and mechanical properties.

Purpose of the Study:

• To compare the efficacy of three single-file NiTi rotary systems—WaveOne Gold, Hyflex EDM, and XP-endo Shaper—in reducing Enterococcus faecalis bacterial load in infected root canals.
• To evaluate the null hypothesis that no significant difference exists among these NiTi systems in bacterial reduction.

Main Methods:

• Seventy-four mandibular premolars with straight, round canals were selected and artificially infected with E. faecalis for four weeks.
• Root canals were instrumented using one of three single-file NiTi systems: WaveOne Gold, Hyflex EDM, or XP-endo Shaper.
• Bacterial samples were collected pre- and post-instrumentation using sterile paper points to quantify bacterial load (CFU/mL).
• Scanning Electron Microscopy (SEM) was used to assess canal topography and debris removal in five samples per group.

Main Results:

• Pre-instrumentation bacterial load was approximately 9.64 log CFU.
• Hyflex EDM and XP-endo Shaper demonstrated significantly greater bacterial reduction compared to WaveOne Gold (P=0.00).
• SEM analysis revealed thick, dense debris in WaveOne Gold samples, while Hyflex EDM and XP-endo Shaper showed disrupted biofilm structures with both clean and debris-laden areas.
• Complete bacterial eradication was not achieved by any system.

Conclusions:

• Instrumentation with Hyflex EDM and XP-endo Shaper achieved superior bacterial reduction in straight, round premolar root canals compared to WaveOne Gold.
• None of the tested single-file NiTi systems could completely eliminate Enterococcus faecalis from the root canal system.
• The findings suggest that system design and mechanical properties influence the efficacy of bacterial reduction during root canal preparation.