Fact Sheets Reference Articles About the Program Infection Control Oral Cancer Children's Oral Health Surveillance Water Fluoridation Educational Materials Infection Control in Dentistry Waterborne Disease Transmission Dental Unit Quality General Information Adverse Health Effects American Dental Association's Statement on Dental Unit Water Lines General Information Reports in the scientific literature suggest that the microbiological quality of water used in dental treatment frequently may not be acceptable for dental care delivery. This issue was first reported more than 30 years ago and recently has resurfaced due to an increased awareness of potential occupational hazards and concern about the increasing numbers of immunocompromised patients seeking dental treatment. The current problem with the water quality primarily centers around the formation of microbial biofilm along the walls of the long, narrow-bore tubing that furnishes cooling and irrigating water to dental hand instruments.
Dental plaque is perhaps the most well known biofilm.
Once formed, these biofilms serve as a reservoir, significantly amplifying the numbers of free-floating microorganisms in the water exiting the waterlines. The dental water line provides an ideal environment for microbial colonization. Not only do the materials used in dental unit construction support the formation of biofilms, but the small diameter of the tubing creates a high surface to volume ratio for enhanced biofilm growth. Also, due to a property of fluid dynamics known as laminar flow, the rate of water flow is greatest in the center of the tubing and decreases to near zero at the tubing surface. The results in virtually stagnant conditions at the tubing wall interface even when water is flowing.