A valve or device integrated into a variety of dental instruments connected to dental unit waterlines (DUWLs). They are used in the patient's mouth (e.g. ultrasonic scalers, turbine and conventional handpieces) to prevent back siphonage of oral fluids into DUWLs. The requirement for antiretraction devices has been emphasized by studies that demonstrated that oral fluids can be retracted into DUWLs during instrument use. The detection of oral bacterial species and other human-derived microbial pathogens and potential pathogens in dental unit water has provided convincing evidence for probable failure of antiretraction devices. Currently, best practice recommends that dental handpieces should be operated to discharge water and air for a minimum of 20–30 seconds after each patient to flush out patient material and oral fluids that may have been retracted into the handpiece air, or waterlines.
Coleman D. C., O'Donnell M. J., Shore A. C., Swan J., Russell, R. J. The role of manufacturers in reducing biofilms in dental unit waterlines. Journal of Dentistry 2007;35:701–11.