DANB Dental Waterline Safety 2

Question 1

What is the maximum acceptable level of heterotrophic bacteria in dental unit waterlines per CDC recommendations?

Accepted Answer

500 CFU/mL

Answer

The CDC recommends no more than 500 CFU/mL, matching the EPA drinking water standard. Without maintenance, waterlines can exceed 200,000 CFU/mL.

Question 2

What is the primary cause of bacterial contamination in dental unit waterlines?

Accepted Answer

Biofilm formation on inner surfaces of narrow-bore tubing

Answer

Biofilm—microorganisms encased in polysaccharide matrix adhering to inner tubing walls—is the primary contamination source.

Question 3

Which type of water must be used for surgical procedures in a dental setting?

Accepted Answer

Sterile water or sterile saline through sterile tubing

Answer

For surgical procedures involving bone cutting or tissue reflection, sterile irrigating solutions through sterile delivery systems are required—not standard waterlines.

Question 4

How frequently should dental unit waterlines be flushed at the beginning of each workday?

Accepted Answer

20-30 seconds

Answer

The CDC recommends at least 20-30 seconds to discharge stagnant overnight water, though flushing alone does not eliminate biofilm.

Question 5

What role do independent water reservoir bottles play in dental waterline management?

Accepted Answer

They allow use of treated or distilled water, isolating the unit from municipal supply biofilm

Answer

Self-contained systems provide independence from municipal supply, allowing precisely dosed chemical treatments and lower starting bacterial loads.

DANB Infection Control Exam Practice Test

DANB Infection Control Exam Practice Test

DANB Dental Waterline Safety 2