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* Contaminants in dental water line and air line

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“Dirty Dental Water” aired on ABC news.


Here are the articles of 1999 and 2000 about unsafe or harmful dental water that were aired.


:: Article from abc news


abcdentist Dirty Dental Water
20/20 Finds High Bacteria Levels Because of its design, dental equipment holds stagnant water in which potentially dangerous bacteria develops quickly. (


Feb. 18 — For many of us, going to the dentist is a traumatic experience.
The poking and drilling that goes on for those few hours does not make any future visits any more inviting. Now imagine that the water used during all of those dental procedures was so laden with bacteria, some experts compare it to pond scum.
20/20’s Arnold Diaz wanted to find out how widespread the problem is. The results of a 20/20 investigation revealed startling levels of bacteria. Almost 90 percent of the water samples tested did not meet federal drinking water standards, and two-thirds of them contained oral bacteria, from the saliva of previous patients.
The test also compared the water from a number of dentists’ offices with water from public toilets. In nearly every case, it found that the water from the toilets was cleaner than the water going into the patients’ mouths.

Equipment Design Problems
Why is dental water often full of bacteria? The problem stems from the design of the water lines that feed the dental tools. Underneath the chair and tied to all the equipment visible in the office are tubes that hold the water used in procedures.
When the instruments are not in use, the water sits inside the tubing and stagnates. The small number of environmental bacteria naturally found in the water quickly multiply and clings to the walls of the tubing. When the equipment is used again, the bacteria can be flushed into the mouths’ of patients.

Potential Hazards
Professor Robert Staat, a microbiologist with the University of Louisville Dental School, tested the water from more than 60 dental offices across the nation. He says the organisms found in the water are environmental bacteria and generally not harmful to most people. But, Staat says, “You shouldn’t be exposed to these levels of bacteria when you’re in a health-care facility.”
Dr. George Merijohn, a periodontist who has studied and written about the problem, explains the bacteria can potentially cause disease, especially to people who have weakened immune systems. Any procedures like gum surgery, root canals, and tooth extractions are riskier because they expose the gum line.
“It’s an open wound, and that’s bone, and that’s why in medical surgery they never think of using anything but sterile saline or sterile water,” Merijohn says.

Safe Alternatives
Even though most patients are unaware of the situation at their dentist’s office, the American Dental Association has known of the problem for a number of years. It set a goal to clean up dental water by the year 2000 and instructed manufacturers to come up with possible solutions.
For example, Merijohn uses sterile tubing and disposable bags of sterile saline for his dental tools. Improvements have been made in ultrasonic scalers, used for teeth cleanings, so they can deliver sterile water. Also on the market are water-line filters, which trap bacteria and chemical treatments to flush out the lines.
Still, Merijohn believes most dentists are still using contaminated water in their offices.

Ask Your Doctor
How serious is the risk? ADA spokesman John Molinari says there is no published evidence of a serious health risk. But are people getting sick from the bacteria found in dental water? “For healthy people, I do not have any concern,” he says.
Molinari says we can expect major strides in the process of updating dental equipment over the next couple of years. In the meantime, the next time you sit in the dentist’s chair, you may want to ask what they’re doing to clean their water lines.


:: Article from and other papers


Below is a recent news release from Wayne Obie:

Date: Sun, 20 Feb 2000 12:42:20 -0500
From: Wayne Obie
Subject: NEWS RELEASE – Fresh Water or Pond Scum
For Immediate Release
February 20, 2000

Water In Dentists Office Compared to Pond Scum

A News feature aired on ABC’s 20/20 News Magazine compared the water used in Dental Offices to Pond Scum.

The 20/20 investigation revealed that “almost 90% of the water samples tested did not meet federal drinking water standards, and two thirds of them contained oral bacteria from the saliva of previous patients.”

20/20 also compared water from a number of dentists offices with water from PUBLIC toilets and found in nearly every case that the water from the toilets was cleaner than the water going into the patients mouths.

ADA spokesperson John Molinara stated “that there is no published evidence of serious risk” (Where have you heard that before?) However, Dr. George Merijohn, a periodontist who has studied and written about the problem, explains that “the bacteria can potentially cause disease, especially in people with weekend immune systems. Any procedures like gum surgery, root canals and tooth extractions are riskier because they expose the gum line. It’s an open wound” explains Merijohn, “and that’s why in medical surgery they (doctors) would never think of using anything but sterile saline or sterile water”.

In response to receiving this information a spokesperson for CFMR (Citizens for Mercury Relief) stated that “this is just one example of uninformed consent in the dental industry and one more very serious reason that the A.D.A. and the C.D.A. should be disbanded in favour of ‘Citizens Review Boards’. It is obvious that these organizations do not and have never acted in the best interest of the patient.”

CFMR, who is scheduled to release tomorrow for distribution – Petitions calling for the elimination of the A.D.A and the C.D.A,. and for the banning of mercury in Canada and the U.S , indicated that in light of this new information that they would be adding precautions to their already published “Checklist for Visiting Your Dentist” and be encouraging all dental patients to start collecting water samples from their dentists. Further information regarding this is expected to be published on CFMR’s web site later this week.

Full transcript as well as live video and audio links to the 20/20 Program can be found on CFMR’s Web Site at
The ADA responded very quickly to this threat. A well-stocked armoury of reassuring statements is available at since Feb 11, a week before the ABC’s feature was aired. The problem has been touched on by the ADA years ago, but has it been solved at the practical level?

A MEDLINE search for “legionella” and “dental” yielded 30 hits. Below are the abstracts of six articles. Contamination of waterlines with the deadly Legionella has been known to the dental world for at least 15 years, and this is only one of the microorganisms involved.

J Dent Res 1985 Dec;64(12):1382-5
Prevalence of Legionella-specific IgG and IgM antibody in a dental clinic population.
Fotos PG, Westfall HN, Snyder IS, Miller RW, Mutchler BM

This study was undertaken to determine the frequency of Legionella infection in a dental clinic setting. Serum samples from 270 dental clinic personnel were evaluated using an enzyme-linked immunosorbent assay to detect Legionella-specific IgM and IgG antibodies. The pooled-species whole-cell-antigen preparation used in these assays was derived from six Legionella pneumophila strains and one strain each from Legionella bozemanii and Legionella micdadei. Significant levels of IgG and IgM antibodies were found in 20% and 16%, respectively, of the samples. This compares with 8% and 10%, respectively, for a randomly selected non-clinical group from the region (P less than 0.005). Samples from clinic personnel with significant IgG titers (greater than 1:128) were also evaluated for activity to each of the eight single-species antigens, with the following results: L. pneumophila, 45% (combined six strains); L. micdadei, 37%; and L. bozemanii, 18%. Comparing individuals’ “years spent in the clinic environment” with the incidence of significant antibody levels strongly suggests that the risk of Legionella infection increases proportionately with increased clinic exposure time (P less than 0.05). Analysis of these data implies that Legionella may be present in the dental clinic environment, thus creating an increased risk for clinical personnel or patients.

Epidemiol Infect 1987 Aug;99(1):159-66
Widespread Legionella pneumophila contamination of dental stations in a dental school without apparent human infection.
Oppenheim BA, Sefton AM, Gill ON, Tyler JE, O’Mahony MC, Richards JM, Dennis PJ, Harrison TG

Following isolation of Legionella pneumophila from a special dental station water circuit, used primarily to cool high-speed dental drills which produce fine aerosols, a case finding and environmental survey was undertaken. Widespread colonization of the dental stations was found and the results suggested that amplification of the background levels of L. pneumophila was taking place within the stations. However there was no evidence for transmission causing human infection.

J Dent Res 1988 Jun;67(6):942-3
Serological examinations for antibodies against Legionella species in dental personnel.
Reinthaler FF, Mascher F, Stunzner D
Hygiene Institute, University of Graz, Austria.

Serum samples from 107 dentists, dental assistants, and dental technicians were examined with an indirect immunofluorescence test for antibodies to Legionella pneumophila SG1-SG6, L. micdadei, L. bozemanii, L. dumoffii, L. gormanii, L. jordanis, and L. longbeachae SG1 + 2. Thirty-six (34%) employees from dental personnel from 13 practices showed a positive reaction for antibodies to Legionella pneumophila. Only five samples (5%) from a control group (non-medical workers) were positive. Of the 36 positive serum samples, 13 (36%) reacted with Serogroup 6, 12 with SG 1 (33%), 12 with SG 5 (33%), and three with SG 4 (8%), and eight samples were positive for antibodies to other Legionella species. Dentists had the highest prevalence (50%) of L. pneumophila antibodies, followed by assistants (38%) and technicians (20%). These results indicate that dental personnel are at an increased risk of legionella infection.

J Hosp Infect 1990 Jul;16(1):9-18 Related Articles, Books
Published erratum appears in J Hosp Infect 1990 Nov;16(4):393
The efficacy of chlorination and filtration in the control and eradication of
Legionella from dental chair water systems.
Pankhurst CL, Philpott-Howard JN, Hewitt JH, Casewell MW
Department of Oral Microbiology, King’s College School of Medicine and Dentistry, London.

The apparent failure of hyperchlorination and continuous dosing with chlorine to eliminate legionellae from a dental teaching hospital water supply prompted a prospective study to evaluate charcoal filters as a means of decontamination. Legionella pneumophila serogroup 10 and L. bozemanii serogroup 2 were isolated from dental units yielding 10(1)-10(3) colony forming units (cfu) ml-1 with total bacterial counts in the range 10(2)-greater than 10(4) cfu ml-1. After chair-side installation of charcoal filters bacterial contamination of the dental unit water was prevented and legionellae were initially not detected, but after 7 days the total count returned to pre-filtration levels of greater than 10(4) cfu ml-1; L. pneumophila serogroup 10 was eliminated but L. bozemanii serogroup 2 persisted. These results suggest that neither chlorination nor charcoal filtration deal adequately with the potential hazard of Legionella spp. in dental water.

Int Dent J 1998 Aug;48(4):359-68
Microbial contamination of dental unit waterlines: the scientific argument.
Pankhurst CL, Johnson NW, Woods RG
King’s College Dental Institute, London, UK.

The quality of dental unit water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. The unique feature of dental chair water lines is the capacity for rapid development of a biofilm on the dental water supply lines combined with the generation of potentially contaminated aerosols. The biofilm, which is derived from bacteria in the incoming water and is intrinsically resistant to most biocides, then becomes the primary reservoir for continued contamination of the system. Dental water may become heavily contaminated with opportunistic respiratory pathogens such as Legionella and Mycobacterium spp. The significance of such exposure to patients and the dental team is discussed. There is at the present time, no evidence of a widespread public health problem from exposure to dental unit water. Nevertheless, the goal of infection control is to minimise the risk from exposure to potential pathogens and to create a safe working environment in which to treat patients. This paper evaluates the range of currently available infection control methods and prevention strategies which are designed to reduce the impact of the biofilm on dental water contamination, and are suitable for use in general practice. Bacterial load in dental unit water can be kept at or below recommended guidelines for drinking water (less than 200 colony forming units/ml) using a combination of readily available measures and strict adherence to maintenance protocols. Sterile water should be employed for all surgical treatments.



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