Dental Unit Water Lines (DUWLs) PDF

Dental Unit Water Lines (DUWLs) Dr. Inas Karawia  Learning Objectives Pronounce, define, and spell the Key Terms. Discuss why there is an interest in the decontamination of dental-unit waterlines (DUWLs). Explain why DUWLs contain more bacteria than faucets do. Identify...

Dental Unit Water Lines (DUWLs) Dr. Inas Karawia  Learning Objectives Pronounce, define, and spell the Key Terms. Discuss why there is an interest in the decontamination of dental-unit waterlines (DUWLs). Explain why DUWLs contain more bacteria than faucets do. Identify the primary source of microorganisms in dental-unit waterlines. Explain the role of biofilm in DUWL contamination. 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.  Biofilm "Biofilm" is a community of bacterial cells and other microbes that adhere to surfaces and form a protective slime layer. Found where moisture meets a suitable solid surface, biofilm can contain many types of bacteria, fungi, algae, and protozoa. Viruses cannot multiply in DUWLs Exopolysaccharide slime (EPS) produced by many microbial inhabitants protects the cells from physical and chemical challenges, while water channels within the biofilm carry nutrients to the cells inside the film.  Biofilm Planktonic Individual organisms (free-floating), or even portions of the biofilm near the surface, break off into flowing water in dental waterlines, resulting in contamination of coolant and irrigating solutions.  Biofilm Dental unit waterlines (DUWLs) provide particularly suitable conditions for biofilm formation. Low water pressure, low flow rates, and frequent periods of stagnation also encourage the forming a biofilm layer on tubing walls. Once biofilm is formed, output water often exhibits high levels of bacterial contamination even when the source water is sterile or has very low bacterial counts.  Biofilm Dental personnel are exposed to contaminated DUWLs through inhalation of the aerosol generated by the handpiece and air-water syringe. Fatality of dentists resulting from legionellosis (a serious type of pneumonia caused by Legionella bacteria) has been recorded.  Biofilm The primary source of microorganisms in DUWLs is the public water supply. Saliva can be retracted into DUWLs during treatment. This process is called “suck-back” The public water source has a Colony Forming Unit (CFU) count of less than 500/mL before entering the DUWLs; once that water enters the DUWLs and colonizes within the biofilm, the CFU count increases rapidly. Biofilm Development  What are the health implications of waterline biofilm? Dental unit waterlines (DUWLs) provide particularly suitable conditions for biofilm formation. Low water pressure, low flow rates, and frequent periods of stagnation also encourage the forming a biofilm layer on tubing walls. Once biofilm is formed, output water often exhibits high levels of bacterial contamination even when the source water is sterile or has very low bacterial counts.  Water Quality in Dentistry Good water quality, achieved through environmentally friendly means, is essential for the safe operation of a dental practice. The safety and cleanliness of DUWLs are vitally important to keeping our patients free from exposure to pathogenic bacteria in the biofilm layer.  Methods of Reducing Biofilm It can be minimized with the use of: ○ Self-contained water reservoirs ○ Chemical treatment regimens ○ Microfiltration ○ Flushing of waterlines  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). ○ The dentist and staff control the maintenance of the water system (between the reservoir bottle and the handpieces and syringes). ○ Should empty the bottle daily.  Chemical Agents Biofilm re-growth in DUWLs usually occurs within a week, so DUWLs need to be treated regularly. Elimination of the biofilm can be achieved through the use of a variety of chemical products. Any product used must be: a. Effective b. Compatible with the DUWL components (as recommended) c. Non-toxic to patients or DHCP d. Does not have adverse effects on the environment.  Chemical Agents Introduction of the chemical agent into the waterlines: A. The introduction of the chemical agent into the waterlines may be either intermittent or continuous. 1) The intermittent method of waterline treatment (once a week): a. This method involves placement of the chemical agent in a self-contained water reservoir (the source bottle) and flushing the water lines to allow the chemical to fill all tubing. b. The chemical is left in contact with the tubing for the appropriate contact time advised by the chemical’s manufacturer. Chemical Agents c. Afterwards, the chemical should be flushed out thoroughly with water, depending on the type of chemical disinfectant, the unit is not put into use for a specified number of hours. d. If the unit is connected to the municipal water mains supply, it is essential that the connection is turned off prior to treatment of the waterlines to prevent contamination of mains water with a treatment agent. Chemical Agents 2) The continuous method of waterline treatment: a. This method involves mixing low concentrations of the chemical agent with the dental treatment water. b. This may be achieved either through mixing the chemical agent with the source water in a self-contained system or through placement of the agent in a reservoir inside the dental unit which provides for measured, continuous release into the water passing through the tubing. c. The continuous method may be used alone or may be used after a single regimen of the intermittent type. Microfiltration Cartridge A disposable inline microfiltration cartridge can dramatically reduce bacterial contamination in dental-unit water. This device can be inserted as close to the handpiece or air- water syringe as possible, or in the bottle It should be replaced at least daily. Using filtration cartridges combined with water reservoirs can ensure improved water quality. Flushing Waterlines Flushing for 2 minutes in the morning and 20–30 seconds after each patient should be considered the norm for dental procedures, and longer flushing is suggested after weekends. Flushing at the beginning of the day should be performed without handpieces connected to the waterlines.  Water Quality Monitoring Regardless of the source water, the number of bacterial counts of non- pathogenic bacteria in the water should be as low as reasonably achievable without exceeding 500 Colony Forming Unit (cfu)/ml. A process of monitoring the quality of waterlines regularly.  Water Quality Monitoring The manufacturer’s recommendations for sampling dental unit waterlines should be strictly followed. In the absence of the manufacturer’s recommendations, the following steps should be applied: ○ Clean the air/water syringe waterline, instrument hose waterline, patient cup filler waterline, and spittoon rinse waterline outlets of the dental unit for 2 minutes before collecting water samples.  Water Quality Monitoring ○ Collect 50 ml of water from each outlet. ○ Samples of water should also be taken from independent water reservoir bottles where used. ○ Store the water between 2 and 8˚C and return to the microbiology laboratory for analysis ideally within 24 hours of collection. ○ Labeling information should contain details of each waterline to be sampled, the sender’s reference, the person sampling, date and time of sampling.