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Waterlines, Biofilms and Water Quality

Infection Control, DA116

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Safe Drinking Water

• Coliform Units– Bacteria in water– Indicator of fecal

contamination

• EPA = 500 CFU

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DUWL* Awareness

• Immunocompromised patients• 1990– ADA =200 or less CFU

• Dental Unit Waterlines

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What are “waterlines”?Thin, plastic tubing carries water to

to the patient’s mouth

Air/water syringe Highspeed handpiece

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A big problem!

The dental water system is like a maze with about 60 feet of small bore plastic lines with stagnant water for over 20 hours per day building biofilms

Most dental office water comes from municipal water supply directly to the unit

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Laminar Flow

• Flow of water is nearly stagnant at inner wall surface of tubing, even when water is actively flowing through the center of the tube.

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What are Biofilms?Microorganisms that form on the surfaces inside moist environments; made up of coliform units (CFU)

Scanning laser confocal microscopy showing biofilm/slime matrix inside the waterlines (red=dead microbes, green=live)

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Biofilm Development

• Initial Attachment

• Accumulation

• Release

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How quickly does this occur?

Bacteria populations double every 20 minutes

◦ Example:1 Bacteria @8 AM4096 Bacteria @12 NOON134,217,728 Bacteria @5PM

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YIKES!

• Dental treatment water from non-cleaned system in this image shows >600,000 coliform units per mL

11How does bacteria get into our dental system?

Some of it comes from the original source water. exception =Sterile water

Most of it comes from retraction. This is why some units have higher contaminations than others. It depends on who was seen in the chair and how badly the unit is retracting. Pretty disgusting isn’t it?

Bacteria in Patient #1 gets delivered to Healthy Patient #2

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DUWL Contamination Dynamics

Input: Water quality

Waterline: Biofilm

Output: Retraction and Backflow

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Safe Water Guidelines

CDC - For routine dental treatment, meet regulatory standards for drinking water. <500 CFU/mL of heterotrophic water bacteria.

ADA – "Encourages industry and the research community to improve the design of dental equipment so that by the year 2000, water delivered to patients during nonsurgical dental procedures consistently contains no more than 200 CFU/ml at any point in the time in the unfiltered output of the dental unit."

EPA - The number of bacteria in water used as a coolant/irrigant for nonsurgical dental procedures should be as low as reasonably achievable and, at a minimum, <500 CFU/mL

OSAP - The regulatory standard for safe drinking water of <500 CFU/mL

• Drinking Water Quality

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Solutions:

• Improve the quality of the incoming water

• Control biofilms in the tubing

• Control water quality as it leaves the tubing

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Improve Incoming Water Quality

• Use non-municipal incoming water• Boil or filter any municipal water• For surgical irrigation, use a separate

reservoir or hand syringe filled with sterile water, distilled water, or deionized water– All components, including tubing, must be

single-use disposable or heat sterilized following each use.

• Chemically treat water • Use no water (“dry”)

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Control biofilms in tubing

• Distillation– Purification (not sterilization)

process that may remove volatile chemicals, endotoxins, and some microorganisms from water

• Reverse Osmosis (point of use filtration)– Purification process that produces

potable drinking water• UV radiation (point of use

disinfection)– May not kill some organisms in

drinking water, such as Giardia and Cryptosporidium

• Chemical Treatment– Uses chlorine or sodium

hypochlorite to treat drinking water and recreational water; some organisms are resistant to these chemicals

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Control water quality as it leaves the tubing • Microbial filters• Use HVE with all water sprays• Self-contained water systems– Non-sterile– Sterile

• Autoclavable reservoir– Autoclaving kills bacteria, viruses, fungi, molds, protozoa,

and all viable organisms; however endotoxins and some chemicals remain

• Disposable pouch with autoclavable tubing and fittings• Sterilization filtration• Purchased sterile water should state “USP 23 Sterile”

19Manufacturer’s Devices and Products

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Water treatment options:

• 1) Independent water units can range from $150-$350, and treats water with antimicrobial medicaments

• 2) Chemicals – up to hundred dollars per year – may involve weekly or monthly treatments

• 3) Filters - $3-10 each – may need to change weekly or monthly depending on model

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Dental Office Guidelines

ADA 200 CFU/ml

• At start of each day, run and discharge water from dental units for several minutes

• Run high-speed handpieces 20-30 seconds after each patient to release air and water

• Follow manufacturer’s instructions for proper maintenance of handpieces and waterlines

• Consider other options to improve water quality

• Use sterile saline or sterile water for surgical procedures

CDC no more than 500 CFU/ml

• Flush air/water through handpieces for 20 seconds between patients

• Avoid using dental unit water for procedures involving bone cutting– Use sterile saline or

sterile water

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Procedures

• If a disaster or weather-related event occurs, public health officials may issue a Boil-Water Advisory– Do not use public water supply at this time for

• Dental Procedures• Patient mouthrinsing• Handwashing

• When Boil-Water Advisory is cancelled– Flush incoming waterlines for 1 – 3 minutes– Turn on all faucets in the office for 30 minutes– Disinfect dental unit waterlines according to

manufacturer’s guidelines