Dental Unit Waterlines Chapter 24 Copyright 2009 2006

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

Chapter 24 Lesson 24. 1 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Learning Objectives Pronounce, define, and spell the Key Terms. Discuss why there is a renewed interest in contamination of dental-unit waterlines (DUWLs). Explain why DUWLs contain more bacteria than faucets do. Identify the primary source of microorganisms in dental-unit water. Explain the role of biofilm in DUWL contamination. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Learning Objectives (Cont’d) List the factors in bacterial contamination of dental-unit water. Describe methods to reduce bacterial contamination in DUWLs. Describe the recommendations of the Centers for Disease Control and Prevention (CDC) for dental-unit water quality. Explain the CDC’s recommendation for the use of saliva ejectors. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Introduction Outbreaks of waterborne disease have occurred in a broad range of facilities. Although there is no evidence of a widespread public-health problem, published reports have associated illness with exposure to water from dental units. The fact that bacteria capable of causing disease in human beings are found in DUWLs is reason for concern. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Introduction (Cont’d) In community water, the number of waterborne bacteria is kept to fewer than 500 colony-forming units (CFUs) per milliliter. The water from air-water syringes and dental handpieces often has bacterial levels hundreds or thousands of times greater than those permissible in drinking water. The types of bacteria that are found in dental-unit water are frequently the same types found in community water, but the levels of bacteria found in the dental units are almost always higher. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Background Dental healthcare workers are exposed to Legionella bacteria at a much higher rate than are members of the general public. Dental personnel are exposed to contaminated DUWLs through inhalation of the aerosol generated by the handpiece and air-water syringe. At least one suspected fatality of a dentist resulting from legionellosis has been recorded. Published case reports have described immunocompromised patients in whom postoperative infections developed as a result of contaminated dental water. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Microorganisms in Waterlines The primary source of microorganisms in DUWLs is the public water supply. Saliva can be retracted into DUWLs during treatment. This process is called “suckback. ” Antiretraction valves on dental units and thorough flushing of the dental lines between patients minimize the chance of suckback. The public water source has a CFU count of less than 500/m. L before entering the DUWLs; once that water enters the DUWLs and colonizes within the biofilm, the CFU count skyrockets. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Communities of Bacteria There are two communities of bacteria in DUWLs: One bacterial community exists in the water itself and is referred to as planktonic (free-floating). Ø The other exists in the biofilm attached to the walls of the DUWLs. Ø Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -1 Close-up of a dental tube’s opening. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -2 A, Magnification of biofilm formation on the walls of the tube. B, Cross-section of biofilm formation in DUWL. (Courtesy of Sultan Chemists, Inc, Englewood, NJ. ) A B Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -3 Bacteria in biofilm taken from DUWLs. (Courtesy of Dr. Shannon Mills, U. S. Air Force. ) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Biofilm Biofilm exists in all places where moisture and a suitable solid surface are found. Biofilm consists of bacterial cells and other microbes that adhere to surfaces and form a protective slime layer. Biofilm can contain many types of bacteria, as well as fungi, algae, and protozoa. Viruses, such as the human immunodeficiency virus, cannot multiply in DUWLs. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -4 Bacteria in biofilm dropping into waterlines. Some bacteria are planktonic and enter directly from the municipal water supply. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Methods of Reducing Contamination It is not yet possible to eliminate biofilm, but it can be minimized with the use of: Self-contained water reservoirs Ø Chemical treatment regimens Ø Microfiltration Ø Daily draining and drying of lines Ø Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Self-Contained Water Reservoirs These systems supply air pressure to the water bottle (reservoir). The air pressure in the bottle forces the water from the bottle up into the DUWL and out to the handpiece and air-water syringe. Self-contained water systems have two advantages: Dental personnel can select the quality of water to be used (e. g. , distilled, tap, sterile). Ø Maintenance of the water system (between the reservoir bottle and the handpieces and syringes) is under the control of the dentist and staff. Ø Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -5 Self-contained dental-water unit. (Courtesy of Dr. Ronald Johns. ) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

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 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. (Courtesy of Pamela Landry, RDA. ) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Microfiltration Cartridge A disposable inline microfiltration cartridge can dramatically reduce bacterial contamination in dental-unit water. This device must be inserted as close to the handpiece or air-water syringe as possible. It should be replaced at least daily on each line. The use of filtration cartridges combined with water reservoirs can ensure improved water quality. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig. 24 -7 The Denta. Pure 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 scaler is treated. The cartridges are changed every 40 days. (Courtesy of Denta. Pure, Fergus Falls, Minn. ) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Chemical Agents Chemicals can be used to help control biofilm in two ways: Periodic or “shock” treatment with biocidal levels (levels that will kill microorganisms) of chemicals Ø Continuous application of chemicals to the system (at a level that will kill the microorganisms but not harm human beings) Ø Always check with the manufacturer of the dental equipment to determine which chemical product and maintenance protocol is recommended. Monitor the water quality in the dental unit in accordance with the manufacturer’s recommendations. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Water for Surgical Procedures Dental-unit water should not be used as an irrigant for surgery involving the exposure of bone. Only use sterile water from special sterile water–delivery systems or hand irrigation with sterile water in a sterile disposable syringe. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Flushing Waterlines All DUWLs and handpieces should be flushed in the mornings and between patients. Although this will not remove biofilms from the lines, it may temporarily reduce the microbial count in the water. It will help clean the handpiece waterlines of materials that may have entered from the patient’s mouth. Flushing also brings a fresh supply of chlorinated water from the main waterlines into the dental unit. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Minimizing Aerosols Always use the high-volume evacuator when using the high-speed handpiece, ultrasonic scaler, and air-water syringe. The high-volume evacuator may also reduce exposure of the patient to these waterborne microorganisms. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Using Protective Barriers The dental dam greatly reduces direct contact. The dam also greatly reduces the aerosolization and spattering of the patient’s oral microorganisms onto the dental team. Protective barriers, including masks, eyewear, and face shields, also serve as barriers for the dental team. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.