Infection Control · single question
Why does biofilm occur in dental unit waterlines (DUWLs)?
Show answer and explanation
Correct answer: A. Because of the long, small-diameter tubing and low flow rates
Long, small-diameter tubing AND low flow rates (A) are the primary reasons for DUWL biofilm formation. The conditions favor biofilm:
• Long, narrow tubing: large surface area relative to volume — lots of surface for bacteria to colonize
• Low flow rates: water sits stagnant in lines, especially overnight/weekends
• Room temperature: ideal for bacterial growth
• Retraction: handpieces may suck back oral fluid into the lines
• The resulting biofilm releases bacteria (Pseudomonas, Legionella, atypical mycobacteria) into the water.
• Biofilm is extremely resistant to standard disinfectants — requires specialized waterline treatments.
• This is why flushing protocols + waterline maintenance are critical infection control measures.
• Long, narrow tubing: large surface area relative to volume — lots of surface for bacteria to colonize
• Low flow rates: water sits stagnant in lines, especially overnight/weekends
• Room temperature: ideal for bacterial growth
• Retraction: handpieces may suck back oral fluid into the lines
• The resulting biofilm releases bacteria (Pseudomonas, Legionella, atypical mycobacteria) into the water.
• Biofilm is extremely resistant to standard disinfectants — requires specialized waterline treatments.
• This is why flushing protocols + waterline maintenance are critical infection control measures.
Practice Infection Control questions Infection Control study notes