Research of bacterial contamination in dental unit waterlines

Abstract number: r2086

Göksay  D., Çotuk  A., Zeybek  Z.


The water used in dental unit waterlines (DUWLs) acts as a coolant for the high-speed drills and as an irrigant during dental procedures. There are a number of possible sources of water supplied to DUWLs, including public main water supply connections or water tanks. DUWLs provides an ideal environment for microbial biofilm and proliferation primarily due to the high surface/ volume ratio in the tubing and the character of fluid dynamics in narrow, smooth-walled waterlines. Biofilms can harbour opportunistic pathogens such as Legionella sp., Pseudomonas sp., and therefore dentists, immunocompromised patients may be at risk. The aim of our study was to determine Legionella, Pseudomonas, Total Aerobic Heterotrophic Mezophilic Bacteria (TAHMB) contamination of DUWLs in private dental offices Istanbul city of Turkey.


A total of 59 water samples were taken from high-speed drill, air-water syringe, oral rinsing cup. R2A Agar and Nutrient Agar (NA) were used for TAHMB. Pseudomonas Agar Base with CFC supplement was used for Pseudomonas. Buffered Charcoal Yeast Extract Agar containing glycine, vancomycin, polymyxin, cycloheximide was used for Legionella. In addition two DUs biofilms from the high-speed drill were investigated according to Method of the Sanden et all.


In the United States, the American Dental Association (ADA) and the Centers of Disease Control and Prevention have suggested a standard for DUWLs water of no more than 200 cfu/ml of aerobic heterotrofik bacteria. We found that all of air-water syringe (range 317–46320 cfu/ml), all of high-speed drill (range 370–52240 cfu/ml) and 90% of oral rinsing cup (range 183–119117 cfu/ml) exceed ADA recommendation for dental unit water. We compared bacterial counts on R2A Agar versus NA; results of R2A Agar were significantly higher than NA. Of the 59 water samples examined, 14 (24%) were positive for Pseudomonas sp. All water samples were negative for Legionella sp.


We suggested that bacterial contamination and also biofilms in DUs should be controlled to eliminate opportunistic pathogens and to provide water for dental treatment, which meets public health standards for ADA recommendation.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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