ABSTRACT
Dutch literature is not very clear about whether or not the effluent water/spray of handpieces of dental units meets the Dutch standards of potable water (< 200 CFU/ml and no pathogens). To improve the quality of dental unit water, flushing or purging the waterlines is recommended. In this study the quality of the effluent water/spray of 9 dental units was measured at the beginning of the day before and after 2 minutes flushing (sample size 25 ml) and the end of the day before and after 20 seconds flushing (sample size 5 ml). All units easily met the potable water standards after 2 minutes flushing, but after 20 seconds the effect was less impressive. The overall larger number of bacteria found after 20 seconds flushing can be explained as a matter of chance, whether or not a by turbulence loosened part of the biofilm has entered the small sample taken.
