Effect of in-line bacteriological filters on numbers of heterotrophic bacteria in water emitted from non-autoclavable dental air-water syringes.

ABSTRACT

PURPOSE: To determine the effect of in-line bacteriological filters on the heterotrophic bacterial count of water from non-autoclavable dental air-water syringes. MATERIALS AND METHODS: In-line bacteriological filters were placed in the waterlines of non-autoclavable dental air-water syringes. Filters were placed either as close as possible to the air-water syringe or at a distance of approximately 6 feet (1.8 meters) from the air-water syringe. After routine flushing of water lines and air-water syringes, water samples were collected aseptically. Samples were diluted, plated on NWRI agar, and incubated, and numbers of heterotrophic bacteria per ml were determined. RESULTS: Filtration substantially reduced heterotrophic contamination of air-water syringe water when the filter was placed immediately adjacent to the air-water syringe. However, there was no beneficial effect when the filter was at a distance from the air-water syringe. Furthermore, filtered water containing no detectable heterotrophic bacteria was re-contaminated upon passage through the non-autoclavable air-water syringe.