Biofilm, dental unit water line and its control

Biofilms are well-organized communities of cooperating microorganisms that can include bacteria, algae, fungi and diatoms. Dental unit waterlines (DUWL) are an integral part of dental surgery equipment, supplying water as a coolant, primarily for air turbine and ultrasonic scalers. Surveys of dental unit waterlines (DUWLs) indicate that biofilm formation is a universal problem and great majority of bacteria that have been identified from DUWL are ubiquitous, although present in only low numbers in domestic water distribution systems, but can flourish as biofilms on the lumen surfaces of narrow-bore waterlines in dental units. DUWL contamination and its significance as a factor in nosocomial infection of patients and health care workers has stressed the risk to immunocompromized persons. Not only patients but also dentists and dental personnel are at risk of being infected with opportunistic pathogens such as Pseudomonas or Legionella species by means of cross-infection or after aerosol formation from water emanating from DUWL. Several methods of decreasing the level of contamination in DUWL have been proposed. At present, the goal of this review is to discuss various aspects of biofilm formation and effective standardized disinfecting methods to maintain low bacterial counts in dental water line. This will increase the awareness of potential health risks posed by biofilm formation and provide information on techniques and devices designed to control the microbial contamination of DUWLs.