The role of flushing dental water lines for the removal of microbial contaminants.
OBJECTIVE
This study was designed to determine the role of flushing dental water lines for the removal of heterotrophic plate count bacteria, Legionella spp., and free-living protozoa.


METHODS
Forty dental offices were surveyed in the study. An initial sample and a sample taken after three minutes of flushing were obtained from the air/water syringe at each location. All samples were quantitatively analyzed for heterotrophic bacteria using three bacteriological procedures. The samples were analyzed for the presence of Legionella spp. using cultural, immunological, and molecular procedures and for the occurrence of free-living protozoa using a killed bacteria plate procedure.


RESULTS
The flushing process reduced the level of heterotrophic plate count bacteria by 1.1 to 1.5 log10 CFU/ml. Compliance with recommendations for bacterial levels varied depending on the methodology employed in the analysis. The flushing process did not reduce the occurrence of Legionella spp. or free-living protozoa.


CONCLUSIONS
The results support recent U.S. Centers for Disease Control and Prevention recommendations that the process of flushing dental water lines cannot be relied upon as a sole means of reliably improving the quality of water used in dental treatment.
Rice
Eugene W
EW
U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA. rice.gene@epa.gov
Rich
William K
WK
Johnson
Clifford H
CH
Lye
Dennis J
DJ
D001431:Bacteriological Techniques; D018057:Dental Waste; D016952:Legionella pneumophila / Q000302:isolation & purification*; D017744:Medical Waste Disposal / Q000379:methods*; D014871:Water Microbiology
D018057:Dental Waste; D017744:Medical Waste Disposal