Dental unit waterline contamination can become a very ...



Dental Water Lines

Ceri Blinsmon

DEH 13 Infection Control

Dental Water Lines

In most dental settings, treatment water comes from the city water supply directly into the dental unit. The dental water line unit consists of thin, plastic tubing, which carries water from the city water reservoir, or from an independent water reservoir located on the dental unit. This water is then carried to the high-speed handpiece, air/water syringes, and ultrasonic scaler and ultimately into the patient’s mouth. These waterlines when looked at from an internal perspective can become colonized with a variety of microorganisms, including bacteria, fungi and protozoa. The microorganisms live in a slime layer that protects and feeds them called biofilm. The biofilm attaches to the water lines and allows the microorganisms to survive and thrive (McDowell, Paulson & Mitchell, 2004, para 6).

This is a very serious issue in regards to infection control. Every dental office should understand and demonstrate the best way to reduce the number of these microorganisms or colony forming units (CFUs). The amount of CFUs approved by the Center for Disease Control (CDC) in dental water lines is fewer than 500 (Centers for Disease Control and Prevention, 2003, p 28). The purpose of this paper is to determine whether or not an independent water reservoir filled with distilled water is more efficient at reducing CFUs than city water.

Using independent water reservoirs allows the dentist to use clean water, this is important because new microorganisms are not continually being combined to those already living in the waterlines (Bednarsh, Eklund, & Mills, 1997, para 25). The CDC recommends flushing the water lines on an independent reservoir. It is also important to periodically “shock” treat the bottles used to hold the water with a biocidal level of chemicals. The chemicals that could be used in the “shock” treatment are 5.25% sodium hypochlorite (bleach) or a commercially made product named chlorhexidine gluconate. The “shock” treatment helps to kill the biofilm living in the water lines (Bednarsh, 1997, para 32). Antimicrobial agents can be added to the independent reservoirs that will help treat the water as it passes through the water lines making it safer for the patient.

One of the most important things to remember about independent water reservoirs is to change the water and clean the bottles daily. This step is vital, but can also be detrimental to the independent system if done incorrectly. The tubing inside the bottles should not be touched with human hands. When adding water to the reservoir or disinfecting the container’s caution should be taken when removing the reservoir, if the tubing is touched it will become contaminated. One disadvantage to using an independent water reservoir system is the initial cost, but over time and seeing improved infection control results for the patient will make prove a cost effective choice.

When using city water in dental lines flushing the water lines prior to treatment is definitely recommended. But, flushing the lines doesn’t remove the biofilm. Flushing helps to lower the amount of CFUs exiting the handpiece or air/water syringe, and flushing also may help to bring up some of the chlorinated water from the city supply. City water has a higher number of microorganisms living in it because there is no real way of performing a “shock” treatment or adding chemicals to the main water supply. There is a distinct possibility that some microorganisms could get through the handpiece and infect the patient. The most common microorganisms living in city water are pseudomonas, legionella and mycobacterium (Miller, Palenik, 2005, p 281-283).

DeGaola et al. (2002) study found the following:

Although no disease transmission arising from dental unit water lines microbial contamination has been conclusively documented, there is irrefutable scientific evidence that the water delivered to most dental patients is of poor microbiological quality and often would fail to meet U.S. drinking water standards. Furthermore, evidence suggests that dental personnel and the increasing number of immunocompromised dental patients are being exposed to potentially pathogenic and resistant microorganisms as a result of aerosolization of dental unit water. Of perhaps greater significance is the fact that disease transmission in association with biofilm formation has been well documented in other health care settings. The potential for transmission of disease from contaminated dental unit water lines exists, in at least some populations (para 33).

According to Miller & Palenik (2005) municipal water is not sterile, and there may not be many waterborne microorganisms present, but when the water exits the handpieces and other hoses it may contain more than 100,000 CFUs. It is not possible to predict the quality of municipal water when it enters the dental unit, it is possible to predict the water quality from an independent reservoir (p 278-279).

Are independent water reservoirs filled with distilled water better than using city water lines? The answer would be yes. Distilled water in water reservoirs is important, but upon researching this subject, studies show that the type of water placed in the reservoirs is not as important as how the water gets treated. Ideally distilled or sterile water would be the best type to use. Independent water reservoirs allow the use of antimicrobial agents, are cleaned daily, use clean water, and when “shocked” help to kill biofilm living in the water lines. There are so many extra precautions that can be taken using an independent water reservoir to ensure a patient’s safety. It is important to know that everything that can possibly be done for the health of the patient is actually getting done and using an independent water reservoir system that happens!

References

DeGaola, L.G., Mangan, D., Mills, S.E., Costerton, W., Barbeau, J., Shearer, B., et al. (2002). A review of the science regarding dental water units [Electronic version]. The Journal of the American Dental Association, 133(9), 1199-1206.

Bednarsh, H., Eklund, K.J., & Mills, S. (1997). Dental unit waterlines: check your dental unit water IQ. Access, 10(9). Retrieved November 22, 2007, from

Centers for Disease Control and Prevention. (2003). Guidelines for infection control in dental health-care settings. Morbidity and Mortality Weekly Report, 53(17), 28-30.

McDowell, J.W., Paulson, D.S. & Mitchell, J.A. (2004). A simulated-use evaluation of a strategy for preventing biofilm formation in dental waterlines [Electronic version]. The Journal of the American Dental Association, 135(6), 799-805.

Miller C.H., & Palenik, C.J., (2005). Infection control & management of hazardous materials for the dental team. St. Louis, Missouri: Elsevier Mosby.

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