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Control of microbial contamination in dental unit water systems using tetra-sodium EDTA
R S Percival1, D A Devine, B Nattress
1Department of Oral Biology, Leeds Dental Institute, Clarendon Way, Leeds LS2 9LU, UK. R.S.Percival@leeds.ac.uk
Aim:
To examine the efficacy of tetra-sodium EDTA in controlling microbial contamination of dental unit water systems (DUWS).
Methods And Results:
Ten dental units were treated once a week with either 4% or 8% tetra-sodium EDTA for four or two consecutive weeks, respectively. Before treatment, 43% and 60% of the water samples from the air/water triple syringe and high-speed hand-pieces, respectively, exceeded the American Dental Association (ADA) guidelines of 200 CFU ml(-1) water during a 6-week baseline period. After each weekend treatment, the levels of microbial contamination in all DUWS fell significantly (P < 0.001) to below the ADA guideline. By the end of the week, microbial counts in the outflowing water had returned to baseline levels indicating a transient effect of single doses of tetra-sodium EDTA, and the need for multiple applications. The biofilms were virtually eliminated after a single weekend treatment.
Conclusions:
Tetra-sodium EDTA is effective in controlling microbial contamination in DUWS.
Significance And Impact Of The Study:
Inexpensive, effective and safe products for reducing the microbial load of water from DUWS are needed to meet ADA and other national guidelines. Tetra-sodium EDTA can significantly reduce microbial biofilms and bacterial counts in outflowing water, and is compatible for use in DUWS.
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