[Quality of water of dental units. A survey in the region of Berne, Switzerland].

: The aim of this study was to assess the microbial contamination of the water from 175 dental units, which had not been in use for at least 12 hours, and to determine the usefulness of rinsing the water lines for 3 minutes. Only 10% of all units fulfilled all criteria for drinking water. Frequently the total bacterial counts markedly exceeded 100 CFU/ml. In all cases the rinsing decreased bacterial loads significantly. Bacterial contamination of water lines increased with the time the dental units remained unused. It is recommended to rinse dental unit water lines daily for at least 3 minutes before working on patients.