An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England.
OBJECTIVE
To evaluate and improve upon the quality of water emanating from the dental unit waterlines (DUWLs) which supply irrigation for dental handpieces and triple spray syringes in general practice.


METHODS
A prospective clinical audit.


METHODS
Seventy-two general dental practices in the East of England.


METHODS
In 2006, 124 dentists initially registered to participate in the audit. By 2007, 72 had begun and by 2008, 68 had completed the project. This involved collecting samples of water discharged from the DUWLs in the dental practices both before the start and mid-way through a morning session. These were tested microbiologically at a United Kingdom Accreditation Service testing laboratory.


METHODS
Before the audit, 56% of the DUWLs were reportedly flushed through for 2 minutes at the start of the day, 29% were purged for 20 seconds in between each patient, 50% were treated with a wide range of different disinfectant solutions, 44% were drained down dry at the end of the day and 9% had no cross-infection control measures applied to them at all. In the audit, 100% used a disinfectant solution alone, predominantly either Alpron or Sterilox.


METHODS
The minimum audit standard set was for the water samples to meet the United States' Centers for Disease Control and Prevention (CDC) guideline on the quality of DUWL water, namely that the United States' Environmental Protection Agency (EPA) regulatory standards for drinking water be adopted, in that no more than 5% of water samples should be contaminated with total coliforms and that they should not have more than 500 colony forming units per ml (cfu/ml) of heterotrophic water bacteria. However, the participating dentists were encouraged to try and achieve the more stringent European Union (EU) standards for potable (drinking) water, namely for the water samples to have neither Escherichia coli nor any other faecal coliforms present and for the aerobic colony count to be less than 100 cfu/ml at 22°C after 72 hours of culturing.


RESULTS
In the pre-audit survey, none of the 72 DUWL water samples were contaminated with E. coli but in five of them (7%) coliforms were recovered. Only 25% reached the EU potable water standard, of which 11% had zero planktonic bacterial contamination. Three percent were above the EU standard but below the CDC guideline/EPA regulatory drinking water standard, while alarmingly, 72% of them failed to reach this minimum audit standard altogether. However, after the application of a suitable disinfectant for at least a month, the audit revealed that E. coli still remained absent in the water samples taken from the 68 DUWLs that completed the project and in only one (1.5%) were coliforms recovered. Remarkably, nearly 81% reached the EU potable water standard, of which 54% had zero planktonic bacterial contamination, with nearly an additional 6% reaching the American CDC/EPA standard and with only 13% failing outright.


CONCLUSIONS
Clinical audit using appropriate DUWL disinfectants can result in the improvement of the quality of water that is discharged through DUWLs, thereby minimising both the risk of cross-infection to vulnerable patients as well as to dental staff chronically exposed to contaminated aerosols.
Chate
R A C
RA
Orthodontic Department, Essex County Hospital, Lexden Road, Colchester, UK.
D002487:Centers for Disease Control and Prevention, U.S.; D054869:Clinical Audit / Q000379:methods; D015169:Colony Count, Microbial; D019551:Dental Disinfectants / Q000494:pharmacology; D003748:Dental Equipment / Q000592:standards; D004492:Edetic Acid / Q000494:pharmacology; D004739:England; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification; D005062:European Union; D005792:General Practice, Dental; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019552:Infection Control, Dental / Q000379:methods*; D011446:Prospective Studies; D012973:Sodium Hypochlorite / Q000494:pharmacology; D014481:United States; D014484:United States Environmental Protection Agency; D014871:Water Microbiology / Q000592:standards; D014881:Water Supply / Q000592:standards
C472596:Alpron; D019551:Dental Disinfectants; C118085:superoxidized water; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D012973:Sodium Hypochlorite