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Infection Control · single question

What is the primary reason to evaluate dental unit waterlines (DUWL)?

  1. To ensure water temperature is adequate for irrigation
  2. To maintain microbial counts at or below 500 CFU/mL
  3. To prevent calcium scaling in handpieces
  4. To detect fluoride content
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Correct answer: B. To maintain microbial counts at or below 500 CFU/mL

  • A. Incorrect. Water temperature optimization is not the rationale for DUWL monitoring.
  • B. Correct. Dental unit waterlines can develop biofilm and harbor microorganisms. The CDC and ADA recommend that water used during dental treatment should meet the EPA standard for DRINKING WATER: ≤500 CFU (colony-forming units) per mL of heterotrophic bacteria. Regular monitoring and treatment (chemical flushes, filters) are required to maintain this standard.
  • C. Incorrect. While calcium scaling can affect handpiece performance, the primary regulatory concern for DUWL evaluation is MICROBIAL CONTAMINATION.
  • D. Incorrect. Fluoride content is not a concern in dental unit waterlines.

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