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How does time-dependent dental unit waterline flushing affect planktonic bacteria levels?
Charles M Cobb1, Christopher R Martel, Sidney A McKnight
1Department of Periodontics, School of Dentistry, University of Missouri-Kansas City, 64108, USA. cobbc@umkc.edu
Journal of Dental Education
|May 23, 2002
Summary
Flushing dental unit waterlines (DUWLs) for up to four minutes significantly reduces planktonic bacteria. However, bacterial levels in DUWLs still exceed American Dental Association (ADA) recommendations after flushing.
Area of Science:
- Dental hygiene
- Microbiology
- Infection control
Background:
- Dental unit waterlines (DUWLs) can harbor microbial biofilms.
- Biofilms in DUWLs pose a risk to patient and dental staff health.
- Untreated DUWLs require effective decontamination strategies.
Purpose of the Study:
- To assess the impact of timed waterline flushing on biofilm presence in dental unit waterlines (DUWLs).
- To quantify bacterial reduction in DUWLs after specific flushing durations.
Main Methods:
- Collected water samples from twelve high-speed handpiece DUWLs.
- Quantified planktonic bacteria using colony-forming units (CFUs) before and after 2, 3, and 4-minute flushing intervals.
- Examined waterline tubing segments using scanning electron microscopy to confirm biofilm presence.
Main Results:
- A statistically significant reduction in CFUs was observed at all flushing intervals compared to baseline (p<0.01).
- Significant bacterial reductions were noted between successive time intervals.
- After four minutes of flushing, all DUWLs maintained CFU levels exceeding ADA recommendations.
Conclusions:
- Timed water flushing of DUWLs effectively reduces planktonic bacteria.
- Extended flushing (up to 4 minutes) is insufficient to meet current ADA microbial level guidelines for DUWLs.