Unit-Oral® : how to prevent and control water contamination on dental unit using rapid water testing.

Every day, water used during routine dental procedures exposes patients to millions of micro-organisms. Treated city water typically enters a dental office with very few viable bacteria present. But by the time that water runs through pipes, tubing, and dental delivery systems, micro-organisms have been given the opportunity—and sometimes, prime conditions-to grow exponentially in dental unit waterlines.

Potential source of contamination

Dental chair units are equipped with a flexible, plastic tubing that supply water to all dental instruments (air/water syringe, turbine, rinsing equipment). Biofilm and bacterial contamination are often observed in the dental unit water.

Poor microbiological Dental Unit Water (DUW) quality associated with generated aerosols during dental procedures, could be an important source for transmission of pathogenic bacteria. Dental unit waterline problems result mainly from how water is used in the operatory and from the design of dental delivery units :

  • Low flow rates and long periods of stagnation
  • Small-diameter waterlines and high surface-to-volume ratio
  • Increasing water temperature
  • Waterline termination, or “dead legs”
  • Contaminated source water and “suck back” from patients.

Bacteria strains identity and quantity associated with poor dental unit water quality

Bacterial numbers per ml in DUW can reach several millions overnight.

Opportunistic bacteria such as Legionella pneumophila and Pseudomonas aeruginosa have previously been revealed in DUW  biofilms.

A symposium held at Trinity Collège, Dublin, Ireland, in Sept 2006 reached the consensus that output water quality should comply with ADA standard (Total Viable Count [TVC] <200 cfu/ml). This count should not include human pathogens (E.coli, Entecoccus spp, Pseudomonas aeruginosa, Legionella pneumophila).

  • In Europe, it is recommended that only water of drinking water quality may be used in dental chair unit. In Europe, drinking water quality is TVC < 200 CFU/ml.
  • In USA/Australia , drinking water quality is TVC < 500 CFU/ml
  • In Japan , drinking water quality is TVC < 100 CFU/ml
  • In France, water for any medical application should be TVC <500 CFU/ml and absence of Pseudomonas aeruginosa for sourcing water (entrance water) and TVC< 200 CFU/ml in  wayout with absence of.

Legionnella pneumophila and Pseudomonas aeruginosa associated diseases

People who get sick after being exposed to Legionella can develop two different illnesses: Legionnaires’ disease and Pontiac fever. A recent study has reported a transmission of L. pneumophila from a dental unit to a patient, who died from septic shock. The role of the dental unit as source of infection was proved by molecular fingerprinting techniques. P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses ( such as pneumonia and various sepsis syndromes). P. aeruginosa typically infects the airway, urinary tract, burns, and wounds, and also causes other blood infections.

Real Time PCR for Unit-Oral® TVC analysis

Microbial DNA and RNA  extraction from 5 ml water. RNA/DNA amplification with DNA probes and primers. Bacterial Universal probe for  Total Viable Count (TVC)  and specific  RNA/DNA bacterial specific sequences for Legionella pneumophila, Pseudomonas aeruginosa, E.coli , Enterococcus spp.

Unit-Oral TVC RT PCR limit of detection is equivalent to 100 CFU /ml

The objectives of Unit-Oral® and Benefit for the dental clinic

Reduction of the exposure to potentially pathogenic agents

Create a climate of trust for your staff and your patients
Safe water usage

Better dental chair maintenance

longer life  of dental chair pipes, tubing, and dental delivery systems

Technical recommendations

For dentists and hygienists, it is advised to carry out an analysis in the following situations :

  • Early morning before first patient visit
  • Always measure at the same hour
  • Spray water for 30 seconds before sampling
  • Collect 5 ml minimum with the Unit-Oral sampling kit
  • Do not store the sample more than 6 hours before shipment for analysis