John A. Molinari, Ph.D.

	News reports and clinical articles documenting microbial infections traced back to contaminated public and healthcare water sources have increased at an alarming rate within the last decade (

). Four incidents in dental practices have also been reported during this period.

 Localized cutaneous infections, bacteremias, and even disseminated, life-threatening diseases have been diagnosed, especially when they develop in immune compromised and/or critically ill patients.
	

Clinicians are asked to devote more attention to understanding possible treatment sequelae for the increasing number of compromised patients, while also minimizing microbial exposure for all patients using established infection prevention practices.
	
	Efforts to prevent contamination of water sources in healthcare settings have improved at a rapid pace. With specific regard to dentistry, colonization of dental treatment water can be greatly reduced by appropriate application of a number of direct and indirect antimicrobial technologies. Progress aimed at addressing this emerging issue has led to the development and availability of a number of products for use in dental settings. Unfortunately, clinicians may become confused by competing and conflicting efficacy claims. In such cases, resultant dental unit waterline (DUWL) infection control procedures can be compromised and/or ineffective due to lack of following proper instructions.
	
	In order to maximize infection prevention efforts, dental professionals should be aware of a few basic guidelines when selecting and using products.
	 

 Most dental unit waterline treatment products are EPA-registered to reduce microbial contamination. Product manufacturers are required to submit appropriate test data to validate and ensure efficacy of their product(s). If used according to the manufacturer’s instructions, EPA-registered products will perform according to its approved label.
		 

 Follow the manufacturer’s instructions for use (IFUs) in order for the product to perform as indicated on the label. Compliance with IFUs is a major factor contributing to success, as well as a common reason for failure of a practice’s dental water infection prevention efforts. The efficacy of products is dependent on properly following IFUs. For example, ongoing protocols may vary from initial protocols and/or some products may be required to sit in the lines overnight as compared to others with a five-minute time frame.
		 

Some products are used to clean (often referred to as “shock”) on a periodic basis, whereas others are meant to be used for ongoing maintenance of DUWLs (often daily or weekly) in conjunction with a cleaner. Treating cleaned waterlines to minimize subsequent microbial colonization may involve the same or a different product. For example, combination cleaner/maintenance system products are available which contain separate waterline cleaning (i.e. “shock”) agents and maintenance chemicals. They are very effective when used appropriately. This is where compliance with a manufacturer’s instructions for use procedures is important. In this instance, manufacturers include both a separate cleaner for periodic use to remove accumulated microbial contaminants, along with a maintenance product for more frequent, routine use. Others, especially those treatments employing the daily application of antimicrobial tablets, call for a separate cleaning solution. It should be noted using bleach as a DUWL cleaner and treatment is not approved by the EPA for dental waterline use. Corrosion and compromise of waterline components can occur with prolonged use of bleach. Multiple highly effective and compatible waterline cleaners have been extensively tested and are readily available with EPA approval for DUWL use.
		 

 Periodic sampling and testing is the most reliable way to evaluate dental water quality. By doing this, it is possible to monitor compliance with IFUs and correct problems which may arise. Recently, the Organization for Safety, Asepsis, and Prevention (OSAP) published a white paper discussing infection control issues along with recommendations for maintaining dental water quality.

 In addition, The Centers for Disease Control and Prevention (CDC), American Dental Association (ADA), and other public health agencies recommend dental treatment water meets the EPA drinking water standard of less than 500 colony forming units per milliliter (CFU/mL). OSAP and an increasing number of state health departments have also recommended quarterly (or more often) testing of waterlines. Two available dental water quality testing options are mail-in water-testing services and in-office methods. Comparisons of both options can be found in 

. Whichever test method is used, it should be able to inform the user of an estimated count of colony forming units per milliliter (CFU/mL). When used appropriately and according to the instructions, monitoring products and services can aid dental facilities in accomplishing dental water quality goals.

	Advances in microbial identification techniques and epidemiological investigations of waterborne outbreaks have allowed improvement in documentation of infections caused by a variety of bacteria. While it is difficult to eliminate waterborne pathogens as natural inhabitants in healthcare water systems, infections caused by these microorganisms are preventable.


	
	Multiple choices are available for controlling and monitoring colonization of water delivery systems and reservoirs, and other technologies continue to be developed. With specific regard to dentistry, the keys for accomplishing DUWL asepsis goals remain the same as for other infection control areas: One, application of basic infection prevention principles; and Two,  compliance with use of approved products.
	
	Colonized waterlines should be cleaned first to remove accumulated microbial and extracellular material prior to implementation of routine treatment procedures. Subsequent compliance with step-by-step IFUs is essential for controlling and maintaining low microbial levels in potable (<500 CFU/mL) treatment water. Periodic testing of water quality can also ensure that ongoing water treatment procedures are effective.
	
	When monitoring is performed as a component of a practice’s DUWL infection prevention routine, it can assist in identifying compliance problems and also provide documentation of water quality.

	1. Ricci MI, Fontana S, Pinci F, et al. Pneumonia associated with a dental unit waterline. Lancet 2012;379:684

	2. Peralta G, Tobin-D’Angelo M, Parham A, et al. Notes from the field: Mycobacterium abscessus infections among patients of a pediatric dentistry practice – Georgia, 2015. Morbid Mortal Wkly Rpt 2016;65:355-356

	3. Hatzenbuehler LA, Tobin-D’Angelo M, Drenzek C, et al. Pediatric dental clinic-associated outbreak of Mycobacterium abscessus infection. J Pediat Dent 2017;6:e116-122

	4. Schonning C, Jernberg C, Klingenberg D, et al. Legionellosis acquired through a dent unit: a case study. J Hosp Infect 2017;96:89-92  

	5. Kanamori H, Weber DJ, Rutala WA. Healthcare outbreaks associated with a water reservoir and infection prevention strategies. Clin Infect Dis 2016;62:1423-1435

	6. Molinari JA. The ongoing challenge of waterborne infections. Inside Dent. August 2017;52-58

	7. Molinari JA. Dental waterline infection control: a work in progress. Dent Econ. February 2017;2

	8. Mills SE, Porteous N, Zawada J. Dental unit water quality: Organization for Safety, Asepsis, and Prevention White Paper Recommendations – 2018. J Dent Infect Control Safety 2018;1:1-27

Articles

While it’s difficult to completely eradicate waterborne pathogens from healthcare water systems, infections caused by these microorganisms are preventable. 

Basic Guidelines for Dental Water Quality

	Efficient reprocessing of contaminated instruments after patient treatment can be complex.

	It involves a series of procedures which utilize specialized equipment, adequate space and healthcare personnel who both understand and can effectively perform required tasks.

	One of the positive aspects of presenting infection prevention seminars is that I see how dental practices progress in this area. Think about it: It wasn’t that many years ago when a number of dental personnel were scrubbing soiled instruments by hand using detergent and running water. As ultrasonic units and instrument washers have become standard in dental facilities, a high level of cleaning prior to sterilization can be reached. Similar progress has been made with new generations of heat sterilizers, especially autoclaves.

	However, even though these developments helped improve infection control practices, basic principles of cleaning, sterilization, and monitoring still should be followed. Unfortunately, they can sometimes be inadvertently overlooked. The following discussion addresses questions related to these procedures.

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Why is it important for cassettes to be dry prior to sterilization?

	Infection control recommendations and sterilizer manufacturers’ instructions for use (MIFUs) state instruments should be dry before packaging and sterilization. To understand why this is important, look at pouches that are removed after an autoclave sterilization cycle.

	Some may be dry, but others can be very wet. This creates a potential problem whereby the pouch paper can be punctured from within by processed instruments. Wet pouches can also cause “wicking,” whereby the wet paper can act as a funnel for external air and bacteria to enter the sterile pack.

	Venting and drying components of sterilizers are designed to remove the same amount of water vapor from the chamber that enters during a prescribed cycle. When pouches containing very wet items are placed in an autoclave, the unit will still remove the amount of water vapor it was calibrated for, but it may not be able to eliminate the excess moisture from packaged instruments. In the absence of placing instruments and cassettes in a separate drying unit, the instruments and cassettes can be air dried (

Alternatively, if using cassettes, one can also use a clean, dry towel or cloth to dry before wrapping/pouching for sterilization. Hand drying loose instruments isn’t recommended due to the risk of sharps injury. In any event, wearing puncture-resistant utility gloves is essential during instrument cleaning, preparation and packaging in order to minimize the risk of a sharps accident.

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	Because instruments in a cassette are already in a tight container, is it necessary to wrap before placing in the sterilizer?

	Yes, they must be either wrapped in either a sterilization wrap (i.e. “blue wrap”) or placed in pouches sized for cassettes (

	Even though cassettes can keep all the instruments together from the chairside procedure through cleaning, rinsing, drying, and sterilization, the presence of their hole patterns requires that they be packaged to maintain sterility after removal from the sterilizer. Remember, while the instruments are sterile at the end of the cycle, as soon as the door is opened and unwrapped cassettes are removed and exposed to air, their contents are clean, but they are no longer sterile.

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Is routine use of Type V integrators in monitoring sterilization a good idea, and can they take the place of biological monitoring?

	Routine monitoring of sterilization cycles using chemical indicators and integrators has become more efficient over the years. Type V chemical integrator strips became available a few years ago and are a valuable addition for monitoring heat sterilizers (

	In contrast to other chemical indicators which can-at best-monitor two sterilization variables, Type V integrator strips contain a steam sensitive material that reacts with all three criteria for proper steam sterilization (i.e. temperature, pressure, time). During the sterilization cycle, the material moves across the wick- ing strip and only registers ACCEPT when the three sterilization conditions are met. Using a test strip in the center of each sterilizer load can serve as an important and early monitoring tool in between required spore testing intervals.

	As useful as these test strips can be, they are not replacements for the gold standard of sterilization – biological monitoring using heat-resistant bacterial spores. Type V integrators are considered analogous to spore testing, but not a replacement. Dental practices still must follow the biological monitoring requirements recommended by the CDC and required by individual states.

Straightening out some of the most misunderstood aspects of optimal dental infection control.