Control of microbial contamination in dental unit water systems using tetra-sodium EDTA.
OBJECTIVE
To examine the efficacy of tetra-sodium EDTA in controlling microbial contamination of dental unit water systems (DUWS).


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.


CONCLUSIONS
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.
Percival
R S
RS
Department of Oral Biology, Leeds Dental Institute, Clarendon Way, Leeds LS2 9LU, UK. R.S.Percival@leeds.ac.uk
Devine
D A
DA
Nattress
B
B
Kite
P
P
Marsh
P D
PD
D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D015169:Colony Count, Microbial; D003748:Dental Equipment / Q000382:microbiology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods / Q000592:standards; D004492:Edetic Acid / Q000494:pharmacology*; D004866:Equipment Contamination; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D014871:Water Microbiology; D014881:Water Supply / Q000592:standards
D004202:Disinfectants; D004492:Edetic Acid