What’s in your water?

April 1, 2005
It has been more than a year ago since the new Centers for Disease Control and Prevention (CDC) Infection Control Guidelines for dentistry have been released, yet many dental practices have still not adopted these guidelines.

by Mary Govani

It has been more than a year ago since the new Centers for Disease Control and Prevention (CDC) Infection Control Guidelines for dentistry have been released, yet many dental practices have still not adopted these guidelines. This seems to be especially true of the CDC’s recommendations on dental unit water quality. Quite possibly, confusion regarding the authority that these guidelines have or a lack of understanding about the issue could be keeping many practices from making the necessary changes.

The confusion over the CDC’s regulatory authority is a simple one to dispel. The CDC is not a regulatory agency like OSHA. It is, however, the standard-setting agency for infectious disease prevention strategies and guidelines. In many states, dental boards have already adopted the CDC guidelines as the standards of care for infection control and patient safety. In this regard, the CDC guidelines have great impact on our dental hygiene practices, since our licenses require us to follow the recognized standards of care.

Research has thoroughly documented the issue of dental water contamination for more than 20 years. In the late 1990s, several television news programs featured stories about the poor quality of water being dispensed from dental units, specifically the microbial contamination. Recently, news stories have reported a similar issue about the water on airplanes.

Microbial contamination in dental units where the water is untreated or unfiltered has been shown to be at levels that significantly exceed the standards for safe drinking water. The microbial contamination is measured in colony forming units (cfu’s). Potable or safe drinking water standards set maximum cfu counts at 500 cfu/ml. Dental unit water has been measured at 100,000 cfu/ml and higher. The cfu counts on airplanes have been in the millions. (Hint: always drink bottled water when you are flying.)

In 1997, the American Dental Association issued a statement on dental unit water quality, which acknowledged that the problem existed, and challenged dental manufacturers to develop devices and materials to help resolve the problem by the year 2000. The industry responded with filters, separate water systems, and disinfectants to treat the dental unit water lines, which met the ADA’s recommendation of 200 cfu/ml. When these products became available, many dental practices voluntarily converted their equipment and adopted new practices to provide better water quality for their patients.

Many, however, are still waiting for some federal or state mandate to require them to make changes in their water delivery systems. If your state dental board has adopted CDC guidelines as standards of care, the mandate is there. If not, we certainly have an ethical obligation to address a well-documented problem, for which there are solutions. In 2003, the CDC recommended that non-surgical dental treatment water contain less than 500 cfu/ml, and that sterile water or saline should be used for surgical procedures.

So, what are the solutions? One solution is to filter the water as it enters the dental unit or before it exits through the air/water syringes, handpieces and scalers. The filters remove microbes and the endotoxins that they produce. When the microbial counts are greatly reduced, the biofilm that normally forms on the insides of the waterline tubing is decreased, allowing for cleaner water delivery to the patients.

Another more common solution is to utilize separate water delivery systems. Nearly all new dental units come with separate water delivery systems, and older units can be retrofitted. These units are not connected to the municipal water supply. The systems allow for all of the water to be purged from the system and for a disinfecting solution to be run into the system periodically.

Like the filters, the disinfectants destroy or decrease the microbes that colonize on the tubing. In addition to providing a mechanism for disinfecting the waterlines, separate water delivery systems also provide other advantages. One is the ability to use distilled water in the dental unit. Although not an infection control strategy, it is advantageous in areas where the mineral content in the water is high (hard water) and mineral deposits could potentially build up and cause blockages. Another advantage is the ability to deliver clean water, and still treat patients in the event of a “boil water” alert. In this case, bottled water can be easily placed in the water reservoirs in order to safely treat patients. Additionally, warm water can be placed in the bottle in order to make the appointment more comfortable for patients, especially those experiencing cold sensitivity.

Many excellent waterline disinfectants are available. Some products are used weekly. The water is purged from the unit, and the solution is then placed in the water bottle/reservoir and drawn into the unit. The solution remains in the unit overnight or over the weekend and is flushed out of the system prior to use. Other products are continuously released into the system through a cartridge, or as a tablet or liquid that is added to the water bottle.

Regardless of which product you select, there are two things that you should not do. Foremost, never use a bleach solution for disinfecting water lines. Although this was recommended several years ago, many units were damaged by the corrosive properties of the bleach. Secondly, avoid the use of over-the-counter and other antimicrobial mouth rinses as waterline disinfectants. Mouth rinses are meant for use in the mouth. Only FDA-approved products should be used as waterline disinfectants. Mouth rinses have not been cleared by the FDA for this purpose, nor has there been any documented research demonstrating their efficacy for this type of use.

Treating dental unit water is only one part of the water quality equation. The CDC also recommends that dental unit water be tested periodically, as a quality control measure. At this time, the CDC does not specify any time intervals for performing the tests. I recommend a baseline test - especially for untreated water - and then quarterly tests for water that is undergoing treatment, or after a new protocol has been implemented. Water test kits that measure cfu counts are available from most dental suppliers.

Mary Govoni, CDA, RDH, MBA, is the owner of Clinical Dynamics, a consulting company based in Michigan. She is a member of the Organization for Safety and Asepsis Procedures and is a featured speaker on the ADA Seminar Series. She also writes a column for Dental Equipment & Materials magazine. She can be contacted at [email protected].