I would like to thank Dr. Christensen for reemphasizing the ubiquitous nature of microbial biofilms in the environment and further reinforcing the responsibility of the dental industry in improving the quality of water used in dental treatment.
Dr. Christensen is correct in observing that dental units are only one of many potential sources of microorganisms in our environment. Indeed, each year in the United States thousands of people are made ill by microorganisms encountered in daily life. Drinking water systems, spas, swimming pools, shower heads, air conditioning systems and grocery store produce misters have all been implicated in waterborne disease outbreaks.
While Legionella, Cryptosporidium and various coliform bacteria most often are isolated, they are not the only examples of organisms associated with waterborne illness. Payment and colleagues,1 for example, have reported that up to 35 percent of gastrointestinal illness in drinkers of tap water may result from consumption of water that meets U.S. drinking water standards.
The fact that dental patients are only exposed to small quantities of colonized water during treatment may well contribute to the paucity of documented disease transmission in dentistry. In the absence of surveillance programs for postoperative complications in dental practice, however, the true epidemiologic picture is very difficult to assess.
Whether or not infection occurs depends on the complex interaction between the numbers of organisms, virulence factors and the immune status of the patient. Since virulence and immunity are the more difficult elements to control, the best means to preclude the possibility of disease transmission is to reduce the numbers of organisms in dental treatment water to levels as low as are reasonably achievable.
While it is true that people may ingest or inhale microorganisms outside of the dental office, these are not therapeutic interventions under the control of the dentist. I still argue that it is inappropriate to deliberately expose patients to potentially pathogenic microbes during dental procedures—especially when the means to reduce the exposure are available. Furthermore, the rationale proposed by Dr. Christensen does not address concerns about long-term exposure for the dental treatment team.
Regarding the assignment of responsibility for correcting the problem, I again agree with Dr. Christensen’s main point. The dental manufacturer bears primary responsibility for developing improved technology to reduce or eliminate the problem. The responsibility, however, is shared with the dental profession.
The situation is much akin to the efforts undertaken over the last several decades to improve national air quality. The cleaner urban air many of us now enjoy came about through the development and marketing of automobiles and fuels that resulted in cleaner exhaust emissions.
However, without these technological advances, the motorist was largely powerless to unilaterally improve air quality other than by not driving. Even with improved automotive design, the automobile owner must still practice good driving habits and perform necessary maintenance to ensure optimal engine function.
(At this point it may also be prudent to note that the aforementioned advances in automotive technology were the direct result of government intervention due to the lack of proactive efforts on the part of the industry and the driving public. Hopefully, this lesson will not be lost on our profession.)
The marketplace encourages a more rapid pace of technological change when consumers choose products that accomplish the job with the least amount of time-consuming and costly effort (including the "people factor"). This is what we see happening right now in the dental industry as companies compete to develop the most economical and reliable systems to improve dental water quality. The dentist’s responsibility lies in choosing to purchase new dental units capable of delivering good quality water or in retrofitting existing equipment.
The fact that Americans spend millions of dollars annually on bottled water and domestic water treatment devices attests to their high expectations for the quality of water they drink. Are they likely to settle for poor quality water in the dental office?
Readers interested in additional recommendations on the responsibilities of manufacturers and clinicians in regards to dental treatment water quality may wish to read the Organization for Safety and Asepsis Procedures position paper on dental unit water lines on the World Wide Web at "www.osap.org/issues/pages/water/duwl.htm".
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