Water hygiene in the dental practice is often underestimated

The underestimated problem: contaminated tubing & dead legs

An underestimated problem with dental units is the tubing inside the dental chair itself. Where no end fitting is attached to this tubing, it can become massively contaminated. Although the problem is known in many practices and staff work against it under the hygiene plan, the result found by externally commissioned laboratories often looks like this: germs (CFU) as well as Legionella, Pseudomonas and E. coli are officially detected.

The disinfectants recommended by manufacturers often contain hydrogen peroxide as the active substance. Hydrogen peroxide is listed under Section 20 of the Drinking Water Ordinance only for oxidation, not for disinfection; for disinfecting installations, DVGW code of practice W 291 gives 150 mg/l hydrogen peroxide compared with 6 mg/l chlorine dioxide.

Feedback from dental practices

Dentists regularly contact biostream® GmbH when findings such as Legionella have been detected in treatment units, asking how to fight them effectively. The treatment unit has to be disinfected as quickly as possible to avoid an interruption to operations. Unfortunately, support from dental depots often does not bring the expected solution, because they often lack the understanding and knowledge of the subject "disinfection of drinking water in treatment units". On closer inspection, hydrogen peroxide solutions are often recommended, which under the current Drinking Water Ordinance are not named as a disinfectant at all.

Our work with dentists has shown that there are many problems in the disinfection of treatment units. Below we report on a case that may sound familiar to you too. (We add to these examples regularly.)

Case 1: Legionella despite correct application, caused by dead legs

A dentist from Göttingen, who had already been dealing with the subject of "disinfecting treatment units" for years, had a problem with Legionella after switching to the bottle-care system. After using biostream® ZERO according to our dosing recommendation, no more Legionella could be detected. The dentist was very satisfied and let us know so shortly afterwards. After a week, however, recontamination of the treatment unit was found, and the dentist's feedback was correspondingly negative. The efficacy of biostream® ZERO for disinfecting treatment units at dental practices was called into question.

Because fresh contamination with Legionella within a week of application is extremely unusual and had not occurred before, our assumption was that there had to be so-called dead legs directly in the treatment unit. Dead legs are sections of tubing with no fitting connected at the end.

The dentist then contacted his dental depot and asked whether there were dead legs in his dental unit. The dental laboratory's answer was: "No!" The dentist then requested a thorough on-site inspection of his unit and agreed to bear the cost himself if NO dead legs were found. If dead legs were confirmed, the dental depot was to bear the cost. The dental depot agreed, and a complete inspection took place shortly afterwards. It turned out that the dental unit contained 2 × 30 cm of water tubing that had been installed for operating a second treatment unit. However, since the dentist did not need a second treatment unit, it had never been fitted. The 2 × 30 cm water hoses were nevertheless still there.

And it was exactly these hoses that had caused disinfection to fail: effective disinfection of treatment units can only work if ALL the drinking-water-carrying lines can be wetted with disinfectant.

Disinfection is not possible in dead legs! Why? In a dead leg, a disinfectant cannot reach the water column. It is a dead end: there is no flow that can carry a disinfectant into this dead leg. For this reason, biostream® ZERO was also unable to fight the Legionella in the dead legs in the case described.

In line with the agreement, the dental depot naturally bore the cost of the inspection. After removing the 2 × 30 cm dead legs, no more Legionella could be detected.

Permanent disinfection of water at the dentist

You have probably wondered whether the problems with disinfecting water in dental units could simply be solved by permanent disinfection. However, the legislator and other institutions concerned with the valuable resource of drinking water took a position on this early on:

• The German Technical and Scientific Association for Gas and Water (DVGW) states in its information magazine (link): "Permanent, prophylactic, chemical/electrochemical disinfection of drinking water in drinking water installations that are built and operated according to the accepted rules of technology is neither necessary nor sensible. Permanent chemical disinfection of drinking water [...] does not correspond to the generally accepted rules of technology. It also conflicts with the minimisation requirement of the Drinking Water Ordinance (TrinkwV 2001) [6]."
• In the Drinking Water Ordinance (link), it states, among other things, on permanent disinfection: "Treatment substances that are added under points b and c and are intended to remain in the drinking water must, in line with the minimisation requirement, be limited in the quantities used to the amount necessary to achieve the treatment goal." This raises the question of how it is to be demonstrated which dose is necessary to achieve the treatment goal. If the same amount is continually dosed, it can happen that disinfectant is added even though NO contamination is present, which would not correspond to the definition.
• In the S2k recommendation (link), prepared by the specialist societies German Society for Hospital Hygiene (DGKH), German Society of Dental, Oral and Craniomandibular Sciences (DGZMK), German Society of Oral and Maxillofacial Surgery (DGMKG), as well as the German Dental Association (BZÄK), the German Working Group for Hygiene in Dentistry (DAHZ) and others, the following key sentence appears: "Even when operating a central disinfection system, the treatment unit manufacturer's specifications on the compatibility of the external and internal disinfection systems, material compatibility, and the Drinking Water Ordinance's 'minimisation requirement' must continue to be observed. The latter states: 'Treatment substances should be added to drinking water during treatment only for compelling hygienic or technical reasons, always only to the extent strictly necessary (minimisation requirement), and under optimal conditions.'"

Continuous or permanent disinfection of dental chairs can be problematic

As you have read, there are clear statements on permanent disinfection. The German Dental Association (BZÄK), as co-publisher of the S2k recommendation, underlines the statement: "Treatment substances should be added to drinking water during treatment only for compelling hygienic or technical reasons, always only to the extent strictly necessary (minimisation requirement), and under optimal conditions."

Now, as a dentist, you can ask yourself how you would argue to the health or trade supervisory authority that you CONTINUOUSLY add a disinfectant (for example, machine-controlled by a BLUE* system), while you cannot CONTINUOUSLY prove that there is regular contamination that makes the permanent use of chemicals necessary.

Our solution for you: without using expensive dosing technology, you can effectively disinfect your dental units quite simply, using the flushing programmes most units already have. All that is needed is to replace the existing or manufacturer-recommended products (mostly based on hydrogen peroxide) with biostream® ZERO.

Although we do not run active advertising in dental trade media and are not an exhibitor at the "International Dental Show (IDS)" either, we have, without advertising, convinced many dental depots and dentists of the efficacy of our product biostream® ZERO.

Facts that speak for us: biostream® products convince

With biostream® concentrates based on chlorine dioxide, you can reliably disinfect drinking water tanks, drinking-water-carrying lines and soda maker bottles. Use the active substance relied on by waterworks, without expensive equipment.

The active substance in biostream® products (chlorine dioxide) has been used to disinfect drinking water in waterworks since the mid-1950s. There, its production requires elaborate and expensive plant, which is no longer necessary now. Produce effective chlorine dioxide yourself, quite simply, and benefit from its efficacy against E. coli, Pseudomonas and Legionella!

Disinfect drinking water lines, dispensing systems and tanks in motorhomes and camping vehicles, as well as on boats and yachts. Drinking water and process water of drinking water quality for industry and commerce can also be disinfected with the concentrates of biostream® GmbH. Talk to us. Our products are also suitable for disinfecting drinking water in times of crisis, for emergency preparedness in the event of a blackout, power cut or other disaster.

Hydrogen peroxide and silver on the list under Section 20 of the Drinking Water Ordinance

The biostream® products ZERO and asepticaPRO comply with DIN 2001-2:2009-04 (drinking water supply from small and non-stationary installations) and are effective across the entire drinking water pH range. Hydrogen peroxide is not named as a disinfectant in the DIN. In the German Environment Agency's current UBA list, too, it is listed exclusively as an oxidising agent, not as a disinfectant.

In DIN 2001-2, silver is named not as a disinfectant but only as a preservative. The DIN includes the following note on this: "Only as an exception, when drinking water is stored without being used over a longer period. Preservation does not replace disinfection where this is required for drinking water that is not in perfect condition."