Evaluation of Disinfectants to Control Microbial Contamination in EU DUWS

Dental Unit Water Systems (DUWS) are used in dental practices to provide water to irrigate the oral cavity, and have been demonstrated to be heavily contaminated with micro-organisms. There is currently no EU Commission guideline applied to DUWS. Objective: to investigate microbial contamination and the application of disinfectants to DUWS for the control of microbial contamination in general dental practice (GDP) in the UK, Denmark, Germany, The Netherlands, Ireland, Greece and Spain. Methods: a range of proprietary products including Sterilex Ultra, Alpron, Sanosil, Oxygenal and BioBLUE were selected to be administered according to the manufacturers instructions to the DUWS in GDP. Water samples were analysed before and after application of the products for microbiological analysis for total viable counts and Pseudomonas aeruginosa to assess the microbial load of the DUWS. Results: The microbial load of DUWS in the different countries was up to 4.4 x 104 cfu.ml-1. The products Sanosil, HWP Blue, Oxygenal and Dentasept (hydrogen-peroxide based products) and Alpron were rated as the most successful products in reducing the microbial counts to < 200 cfu.ml-1. BioBLUE was rated as the next best product although Ster4spray was limited in efficacy and Sterilex Ultra was problematic resulting in clogged and blocked DUWS. Occasional spiking of the microbial load at >200 cfu.ml-1 was observed with a number of the products. Conclusion: whilst the majority of products achieved the necessary reduction in counts to satisfy the American Dental Association criteria of < 200 cfu.ml-1 the use of disinfetants is not necessarily a panacea as practical problems occasionally occurred. The authors would recommend that the dentists monitor the microbial loading of their DUWS and that the EU adopts the same standard as the ADA in that the water in DUWS should contain < 200 cfu.ml-1. This work was supported by the EC (QLK4 –00097-2000).