MICROBIAL-CONTAMINATION OF DENTAL UNIT WATERLINES - THE SCIENTIFIC ARGUMENT

The quality of dental unit water is of considerable importance since p atients and dental staff are regularly exposed to water and aerosols g enerated from the dental unit. The unique feature of dental chair wate r lines is the capacity for rapid development of a biofilm on the dent al water supply lines combined with the generation of potentially cont aminated aerosols. The biofilm, which is derived from bacteria in the incoming water and is intrinsically resistant to most biocides, then b ecomes the primary reservoir for continued contamination of the system . Dental water may become heavily contaminated with opportunistic resp iratory pathogens such as Legionella and Mycobacterium spp. The signif icance of such exposure to patients and the dental team is discussed. There is at the present time, no evidence of a widespread public healt h problem from exposure to dental unit water. Nevertheless, the goal o f infection control is to minimise the risk from exposure to potential pathogens and to create a safe working environment in which to treat patients. This paper evaluates the range of currently available infect ion control methods and prevention strategies which are designed to re duce the impact of the biofilm on dental water contamination, and are suitable for use in general practice. Bacterial load in dental unit wa ter can be kept at or below recommended guidelines for drinking water (less than 200 colony forming units/ml) using a combination of readily available measures and strict adherence to maintenance protocols. Ste rile water should be employed for all surgical treatments.