Europe cracks down on water line maintenance

Scandinavia looks set to introduce tough new guidelines on dental unit water lines highlighting the potentially serious risks to patients and staff presented by untreated dental unit water lines.

Proposed draft legislation on infection control was circulated by Swedish National Bureau for Health and Welfare in August for review by industry professionals. The legislation will be enforced this quarter.

The legislation was proposed following a lengthy investigation in which one witness at a Government hearing in Stockholm stated: "The continued use of untreated dental unit water systems is difficult to justify on professional, moral or ethical grounds."

The new legislation proposes that: "dental unit waterline systems must be tested with microbial tests on a regular basis, at least once a year. If the number of heterotrophic bacteria is higher than 100 cfu/ml it must be documented and measures taken."

Swedish infection control expert, Dr Mikael Zimmerman, who spoke on the topic of infection control at this year's Australian Dental Congress in Adelaide, cited several reports of serious infections in patients which could be traced to dental treatment.

Among the reported cases was a fatal incidence of Legionnaire's disease suffered by a California dentist. A subsequent investigation found the dentist's operatory waterlines contained high levels of Legionella spp.

Biofilm in dental unit waterlines was also a hazard to the dental staff. Dr Zimmerman cited an overseas study which found dentists had the highest prevalence of L. pneumophila antibodies, followed by assistants and technicians - indicating an increased risk of Legionella infection by dental staff compared with a control group of non-medical workers.

Other studies have suggested a possible link between the onset of asthma and endotoxins found in waterline units.

According to Dr Zimmerman, the reported cases and health studies were compelling reasons for all dentists to routinely disinfect dental waterlines to protect their staff and patients.

Dr Zimmerman - an Associate Professor at the Karolinska Institute in Sweden - is about to release a paper on biofilm outlining effective ways of reducing infection risks.

On the local front, A-dec Australia reports it has been receiving an increasing level of enquiries for its ICX water treatment tablets which represent a breakthrough in preventative waterline maintenance.

A-dec Sales and Marketing Manager, Stephen Jennings said A-dec's ICX water treatment tablets clean waterlines and reduce the buildup of deposits, providing a preventive, proactive solution - rather than a reactive one.

"It is wise to have a routine control measure in place to prevent water line contamination and A-dec's ICX tablets are in keeping with the ADA recommendations on dental unit water line maintenance," Mr Jennings said.

Further reading...

• Two patients with immunodeficiency infected with Pseudomonas aeruginosa after dental visit. Identical strain of microorganism identified in the dental unit waterline. Martin MW. Br Dent J 1987;163:152-4.
• 58 (81.2%) out of 71 patients colonized with Pseudomonas aeruginosa identified in dental unit waterlines. The microorganism could be identified in the patients 7 days after dental appointment. Martin MW. Br Dent J 1987;163:152-4.
• Dentists had the highest prevalence of L. pneumophila antibodies, followed by assistants and technicians when compared with a control group of non-medical workers, indicating that dental personnel are at an increased risk of legionella infection. Reinthaler FF et al. J Dent Res. 1988 Jun;67(6):942-3.
• The death of a California dentist from legionellosis. Subsequent to the dentist's death, samples from his dental operatory showed high levels of Legionella spp. It is likely that aerosols from those dental units were the source of the fatal Legionella infection. Atlas RM et al. Appl Environ Microbiol 1995;61:1208-13.
• Nontuberculous mycobacteria, Pseudomonas aeruginosa, Legionella pneumophila, and other bacteria not only survive but proliferate and lie in wait for susceptible hosts. Not only are these organisms intrinsically resistant to high temperatures and biocides, but the biofilms they inhabit enhance their resistance. Barbeau J et al. Can J Microbiol. 1998 Nov; 44(11):1019-28.
• Although the health risks presented by waterline bacterial colonization have yet to be adequately addressed, professional and ethical considerations indicate that steps should be taken to improve the quality of dental unit waterlines. Pederson ED et al. Gen Dent. 2002 Mar-Apr; 50(2):190-5; quiz 196-7.
• The temporal onset of asthma may be associated with occupational exposure to contaminated dental unit waterlines. Most of the organisms isolated from dental unit waterlines are Gram-negative bacteria, which contain cell wall endotoxin. A consequence of endotoxin exposure is the exacerbation of asthma. Pankhurst et al. Prim Dent Care. 2005 Apr; 12(2):53-9.
• The continued use of untreated dental unit water systems is difficult to justify on professional, moral or ethical grounds. Martin MV. Hearing about DUWL in Stockholm Apr. 2005.