Mary Govoni, MBA, RDH, CDA
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).
SCIENCE & TECH
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).
Until recently, there have been only sporadic reports of
disease transmission in dental patients due to contaminated
dental unit water. In 2011, a woman in Italy died from a
Legionella infection that was traced to the dental practice
where she had been treated.
5 In 2015, a hospital in Georgia
reported a cluster of cases of children with Mycobacterium
abscessus infections treated at the hospital, which were traced
to a dental practice where the patients had been treated.
patients had received pulpotomies, and contaminated dental
unit water had been used for irrigation during those procedures.
Even more recently, another report of pediatric patients
receiving pulpotomies and developing M. abscessus infections
is under investigation by the Orange County Health Care
Agency and the California Dental Board. It has been reported
that more than 60 children were hospitalized to treat their
infections, and one young girl reportedly lost part of her
mandible due to the infection.
In the 1990s, the ADA issued a statement on dental unit
water line contamination, which included a recommendation for dental practices to purge or flush their water lines
for at least two minutes at the beginning of each day, to
decrease the microbial contamination by removing stagnant
water in the lines. In addition, the ADA issued a challenge
to dental manufacturers to develop products and technology
that would reduce dental water line contamination. The
manufacturers responded, resulting in the development of
numerous products and technologies that have been cleared