Dental unit water quality revisited

The ability of biofilms to form in dental unit water lines and microbial contamination of water in the dental unit has been well documented. However, some practices still have not addressed the issue of water line contamination, resulting in serious health consequences. A review of water line protocols and water quality is essential for the safety of patients, as well as the dental team.

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The quality of water delivered through a dental unit for treatment has been the subject of much research and discussion over the years. The ability of biofilms to form in dental unit water lines and the microbial contamination of water in the dental unit has been well documented.1-3 This research and the potential for causing bacterial infections in patients during the delivery of dental care led to the establishment of a dental unit water quality standard by the Centers for Disease Control and Prevention (CDC).4

Since this standard was published in 2003, many dental practices have modified equipment and adopted practices to ensure that the water from their dental units contains no more than 500 colony-forming units (CFUs) of heterotrophic bacteria per milliliter of water (<500 CFU/ml). It is important to note here that although CDC guidelines do not have the force of law—as do Occupational Safety and Health Administration rules—they are the prevailing standards of care for patient safety, as recognized by state dental boards, state and local health departments, and the American Dental Association (ADA).