Dental Unit Waterlines Chapter 24 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Dental Unit WaterlinesDental Unit Waterlines

Chapter 24Chapter 24

Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Chapter 24Chapter 24

Lesson 24.1Lesson 24.1


Learning Objectives Learning Objectives

Pronounce, define, and spell the Key Terms.Pronounce, define, and spell the Key Terms. Discuss why there is a renewed interest in Discuss why there is a renewed interest in

contamination of dental-unit waterlines (DUWLs).contamination of dental-unit waterlines (DUWLs). Explain why DUWLs contain more bacteria than Explain why DUWLs contain more bacteria than

faucets do.faucets do. Identify the primary source of microorganisms in Identify the primary source of microorganisms in

dental-unit water.dental-unit water. Explain the role of biofilm in DUWL Explain the role of biofilm in DUWL

contamination.contamination.(Cont’d)(Cont’d)


Learning ObjectivesLearning Objectives

(Cont’d)(Cont’d)

List the factors in bacterial contamination of List the factors in bacterial contamination of dental-unit water.dental-unit water.

Describe methods to reduce bacterial Describe methods to reduce bacterial contamination in DUWLs.contamination in DUWLs.

Describe the recommendations of the Centers Describe the recommendations of the Centers for Disease Control and Prevention (CDC) for for Disease Control and Prevention (CDC) for dental-unit water quality.dental-unit water quality.

Explain the CDC’s recommendation for the use Explain the CDC’s recommendation for the use of saliva ejectors.of saliva ejectors.


Introduction Introduction

Outbreaks of waterborne disease have Outbreaks of waterborne disease have occurred in a broad range of facilities. occurred in a broad range of facilities. Although there is no evidence of a Although there is no evidence of a widespread public-health problem, published widespread public-health problem, published reports have associated illness with exposure reports have associated illness with exposure to water from dental units. The fact that to water from dental units. The fact that bacteria capable of causing disease in human bacteria capable of causing disease in human beings are found in DUWLs is reason for beings are found in DUWLs is reason for concern. concern. (Cont’d)(Cont’d)


IntroductionIntroduction

(Cont’d)(Cont’d)

In community water, the number of waterborne bacteria In community water, the number of waterborne bacteria is kept to fewer than 500 colony-forming units (CFUs) is kept to fewer than 500 colony-forming units (CFUs) per milliliter. per milliliter.

The water from air-water syringes and dental The water from air-water syringes and dental handpieces often has bacterial levels hundreds or handpieces often has bacterial levels hundreds or thousands of times greater than those permissible in thousands of times greater than those permissible in drinking water. drinking water.

The types of bacteria that are found in dental-unit water The types of bacteria that are found in dental-unit water are frequently the same types found in community water, are frequently the same types found in community water, but the levels of bacteria found in the dental units are but the levels of bacteria found in the dental units are

almost always higher.almost always higher.


BackgroundBackground

Dental healthcare workers are exposed to Legionella Dental healthcare workers are exposed to Legionella bacteria at a much higher rate than are members of the bacteria at a much higher rate than are members of the general public. general public.

Dental personnel are exposed to contaminated DUWLs Dental personnel are exposed to contaminated DUWLs through inhalation of the aerosol generated by the through inhalation of the aerosol generated by the handpiece and air-water syringe. handpiece and air-water syringe.

At least one suspected fatality of a dentist resulting At least one suspected fatality of a dentist resulting from legionellosis has been recorded. from legionellosis has been recorded.

Published case reports have described Published case reports have described immunocompromised patients in whom postoperative immunocompromised patients in whom postoperative infections developed as a result of contaminated dental infections developed as a result of contaminated dental water. water.


Microorganisms in WaterlinesMicroorganisms in Waterlines

The primary source of microorganisms in DUWLs is The primary source of microorganisms in DUWLs is the public water supply.the public water supply.

Saliva can be retracted into DUWLs during treatment. Saliva can be retracted into DUWLs during treatment. This process is called “suckback.”This process is called “suckback.”

Antiretraction valves on dental units and thorough Antiretraction valves on dental units and thorough flushing of the dental lines between patients minimize flushing of the dental lines between patients minimize the chance of suckback. the chance of suckback.

The public water source has a CFU count of less The public water source has a CFU count of less than 500/mL before entering the DUWLs; once that than 500/mL before entering the DUWLs; once that water enters the DUWLs and colonizes within the water enters the DUWLs and colonizes within the biofilm, the CFU count skyrockets. biofilm, the CFU count skyrockets.


Communities of BacteriaCommunities of Bacteria

There are two communities of bacteria in There are two communities of bacteria in DUWLs: DUWLs: One bacterial community exists in the water itself One bacterial community exists in the water itself

and and is referred to as planktonic (free-floating). is referred to as planktonic (free-floating).

The other exists in the biofilm attached to the walls The other exists in the biofilm attached to the walls

of the DUWLs. of the DUWLs.


Fig. 24-1 Close-up of a dental tube’s opening.Fig. 24-1 Close-up of a dental tube’s opening.


Fig. 24-2 A, Magnification of biofilm formation on the walls of the tube. Fig. 24-2 A, Magnification of biofilm formation on the walls of the tube. B, Cross-section of biofilm formation in DUWL. B, Cross-section of biofilm formation in DUWL.

(Courtesy of Sultan Chemists, Inc, Englewood, NJ.)(Courtesy of Sultan Chemists, Inc, Englewood, NJ.)

A B


Fig. 24-3 Bacteria in biofilm taken from DUWLs.Fig. 24-3 Bacteria in biofilm taken from DUWLs. (Courtesy of Dr. Shannon Mills, U.S. Air Force.)(Courtesy of Dr. Shannon Mills, U.S. Air Force.)


BiofilmBiofilm

Biofilm exists in all places where moisture Biofilm exists in all places where moisture and a suitable solid surface are found.and a suitable solid surface are found.

Biofilm consists of bacterial cells and other Biofilm consists of bacterial cells and other microbes that adhere to surfaces and form a microbes that adhere to surfaces and form a protective slime layer.protective slime layer.

Biofilm can contain many types of bacteria, as Biofilm can contain many types of bacteria, as well as fungi, algae, and protozoa. well as fungi, algae, and protozoa.

Viruses, such as the human Viruses, such as the human immunodeficiency virus, cannot multiply in immunodeficiency virus, cannot multiply in DUWLs. DUWLs.


Fig. 24-4 Bacteria in biofilm dropping into waterlines.Fig. 24-4 Bacteria in biofilm dropping into waterlines. Some bacteria Some bacteria are planktonic and enter directly from the municipal water supply.are planktonic and enter directly from the municipal water supply.


Methods of Reducing ContaminationMethods of Reducing Contamination

It is not yet possible to eliminate biofilm, but it It is not yet possible to eliminate biofilm, but it can be minimized with the use of:can be minimized with the use of: Self-contained water reservoirs Self-contained water reservoirs Chemical treatment regimens Chemical treatment regimens Microfiltration Microfiltration Daily draining and drying of lines Daily draining and drying of lines


Self-Contained Water Reservoirs Self-Contained Water Reservoirs

These systems supply air pressure to the water These systems supply air pressure to the water bottle (reservoir). bottle (reservoir).

The air pressure in the bottle forces the water from The air pressure in the bottle forces the water from the bottle up into the DUWL and out to the the bottle up into the DUWL and out to the handpiece and air-water syringe. handpiece and air-water syringe.

Self-contained water systems have two advantages:Self-contained water systems have two advantages: Dental personnel can select the quality of water to be Dental personnel can select the quality of water to be

used (e.g., distilled, tap, sterile).used (e.g., distilled, tap, sterile). Maintenance of the water system (between the reservoir Maintenance of the water system (between the reservoir

bottle and the handpieces and syringes) is under the bottle and the handpieces and syringes) is under the control of the dentist and staff. control of the dentist and staff.


Fig. 24-5 Self-contained dental-water unit. Fig. 24-5 Self-contained dental-water unit. (Courtesy of Dr. Ronald Johns.)(Courtesy of Dr. Ronald Johns.)


Fig. 24-6 Reservoir water bottles and lines on self-contained water systems must be Fig. 24-6 Reservoir water bottles and lines on self-contained water systems must be cleaned and disinfected in accordance with the manufacturer’s instructions. The cleaned and disinfected in accordance with the manufacturer’s instructions. The container under the water bottle will catch any solution drips. Note: The dental container under the water bottle will catch any solution drips. Note: The dental

assistant is careful not to touch and contaminate the neck of the bottle. assistant is careful not to touch and contaminate the neck of the bottle. (Courtesy of Pamela Landry, RDA.)(Courtesy of Pamela Landry, RDA.)


Microfiltration CartridgeMicrofiltration Cartridge

A disposable inline microfiltration cartridge A disposable inline microfiltration cartridge can dramatically reduce bacterial can dramatically reduce bacterial contamination in dental-unit water.contamination in dental-unit water.

This device must be inserted as close to the This device must be inserted as close to the handpiece or air-water syringe as possible. handpiece or air-water syringe as possible.

It should be replaced at least daily on each It should be replaced at least daily on each line. The use of filtration cartridges combined line. The use of filtration cartridges combined with water reservoirs can ensure improved with water reservoirs can ensure improved water quality. water quality.


Fig. 24-7 The DentaPure cartridge releases 2 to 6 ppm of iodine as the water passes Fig. 24-7 The DentaPure cartridge releases 2 to 6 ppm of iodine as the water passes over it. The water delivered to the handpiece water, 3-way water syringe, and ultrasonic over it. The water delivered to the handpiece water, 3-way water syringe, and ultrasonic

scaler is treated. The cartridges are changed every 40 days.scaler is treated. The cartridges are changed every 40 days.(Courtesy of DentaPure, Fergus Falls, Minn.)(Courtesy of DentaPure, Fergus Falls, Minn.)


Chemical AgentsChemical Agents

Chemicals can be used to help control biofilm Chemicals can be used to help control biofilm in two ways: in two ways: Periodic or “shock” treatment with biocidal levels (levels that Periodic or “shock” treatment with biocidal levels (levels that

will kill microorganisms) of chemicals will kill microorganisms) of chemicals Continuous application of chemicals to the system (at a level Continuous application of chemicals to the system (at a level

that will kill the microorganisms but not harm human beings)that will kill the microorganisms but not harm human beings) Always check with the manufacturer of the dental Always check with the manufacturer of the dental

equipment to determine which chemical product and equipment to determine which chemical product and maintenance protocol is recommended. maintenance protocol is recommended.

Monitor the water quality in the dental unit in Monitor the water quality in the dental unit in accordance with the manufacturer’s accordance with the manufacturer’s recommendations.recommendations.


Water for Surgical ProceduresWater for Surgical Procedures

Dental-unit water should not be used as an Dental-unit water should not be used as an irrigant for surgery involving the exposure of irrigant for surgery involving the exposure of bone.bone.

Only use sterile water from special sterile Only use sterile water from special sterile water–delivery systems or hand irrigation with water–delivery systems or hand irrigation with sterile water in a sterile disposable syringe. sterile water in a sterile disposable syringe.


Flushing WaterlinesFlushing Waterlines

All DUWLs and handpieces should be flushed in All DUWLs and handpieces should be flushed in the mornings and between patients. the mornings and between patients.

Although this will not remove biofilms from the Although this will not remove biofilms from the lines, it may temporarily reduce the microbial lines, it may temporarily reduce the microbial count in the water.count in the water.

It will help clean the handpiece waterlines of It will help clean the handpiece waterlines of materials that may have entered from the patient’s materials that may have entered from the patient’s mouth.mouth.

Flushing also brings a fresh supply of chlorinated Flushing also brings a fresh supply of chlorinated water from the main waterlines into the dental unit. water from the main waterlines into the dental unit.


Minimizing AerosolsMinimizing Aerosols

Always use the high-volume evacuator when Always use the high-volume evacuator when using the high-speed handpiece, ultrasonic using the high-speed handpiece, ultrasonic scaler, and air-water syringe. scaler, and air-water syringe.

The high-volume evacuator may also reduce The high-volume evacuator may also reduce exposure of the patient to these waterborne exposure of the patient to these waterborne microorganisms. microorganisms.


Using Protective BarriersUsing Protective Barriers

The dental dam greatly reduces direct The dental dam greatly reduces direct contact.contact.

The dam also greatly reduces the The dam also greatly reduces the aerosolization and spattering of the patient’s aerosolization and spattering of the patient’s oral microorganisms onto the dental team.oral microorganisms onto the dental team.

Protective barriers, including masks, Protective barriers, including masks, eyewear, and face shields, also serve as eyewear, and face shields, also serve as barriers for the dental team.barriers for the dental team.


Dental Unit Waterlines Chapter 24 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Documents

dental units

dentalunit water quality

community water

drinking water

dental handpieces

dental lines

dental personnel

public water source