Testing Dental Unit Water Lines / Systems with Dipslides

Visiting the dentist can be daunting enough without the possibility of coming into contact with contaminated water. Although this is unlikely with the policies and cleaning routines that many dental practices have in place, it is definitely worth considering the possibility and making sure that a stringent testing routine is adhered to. Any cases of infection caused by contamination in waterlines are isolated but improving the general health of the water used should still be an every day practice.

Dental water lines are a concern for building up biofilms (slimy film of bacteria, fungi, algae) and as with all dental equipment, water units need to be clean / sterilised.

Dental Dipslides R2A

Various types of bacteria and fungi can be found in dental unit water lines. The contaminants can be tranferred to the water in different ways such as:

  • Mains water
  • Hands
  • Equipment
  • Oral bacteria

Certain conditions will exacerbate the growth of bacteria, these include but are not limited to:

  • Stagnation and low levels of use
  • Warm water conditions
  • Water trapped within tubing creating / harbouring biofilm

Bacteria that can be found in dental water systems:

  • Pseudomonas species
  • Legionella species
  • Nontuberculous mycobacteria
  • Staphylococcus species

Obviously ingesting contaminated water can cause infection (on rare occasions) as well as contact with open wounds but the other danger is the possible inhalation of contaminated water spray / aerosol. This could affect either patient or dental staff. If bacteria is present and it does infect a person then it would most likely be those with compromised immune systems.

Aside from the risk of infection, any highly contaminated water won't taste or smell particularly pleasant.

Many dental practices use solutions / biofilm cleaners to disinfect their units. They also regularly flush waterlines and use filters. Independent water reservoirs are another way for dentists to control the quality of the water. If untreated / not maintained, significant bacteria levels will likely be present within a few weeks with a build up of biofilm possible in only a matter of months.

Using a routine / preventative measures should assist in making sure that the water is clean. Yet, contamination can still be present. Dipslides can be routinely used to check if there is contamination within dental water systems. These tests can be conducted on a regular basis to check the general health of the water lines.

Dentist bacteria water check

The best way to test dental applications is with R2A agar dipslides. R2A agar detects slower growing species such as chlorine tolerant bacteria and heterotrophic species which are commonly found in dental water systems.

Once a dipslide test is conducted, the slide is incubated and analysed to assess the colony forming units that are present on the slide after incubation. This indicates the level of infection present (if any).

In general, less than 100 - 200 cfu/ml is what dental practices should be aiming for when testing dental waterlines. This depends on the location of the dental practice and the policies / regulations in that country. However, tests showing less than 100 colony forming units are more ideal. Really, the water used in the system should meet the same standards as drinking water.

It is recommended that several samples are taken from the same unit when testing to ensure a more accurate all round result.

R2A dipslides will assist the user in assessing the level of infection within dental water. They will not identify individual species. If the user is concerned about the amount of colonies present or wishes to know more about the particular bacteria within the samples, further more specific tests will be required. If more than 200 cfu/ml are present within the samples, the user may wish to review their cleaning practices / equipment before taking another test to confirm that their new routine is effective.


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