It was previously recommended that dental waterlines be flushed at the beginning of the clinic day to reduce the microbial load. However, studies have demonstrated this practice does not affect the biofilm in the waterlines or reliably improve the quality of water used during dental treatment. Because the recommended value of < 500 CFU/mL can not be achieved by using this method, other strategies should be employed. Dental unit water that remains untreated or unfiltered is unlikely to meet drinking water standards.
Commercial devices and procedures designed to improve the quality of water used in the dental treatment are available; methods demonstrated to be effective include self-contained water systems combined with chemical treatment, in-line microfilters and combinations of these treatments. Simply using source water containing < 500 CFU/mL of bacteria (eg, tap, distilled or sterile water) in a self-contained water system will not eliminate bacterial contamination in treatment water if biofilms in the water system will not eliminate bacterial contamination in treatment water if biofilms in the water system are not controlled. Removal or inactivation of dental waterline biofilms in the water system are not controlled. Removal or inactivation of dental waterline biofilms requires use of chemical germicides.
Patient material (eg, oral microorganisms, blood and saliva) can enter the dental water system during patient treatment. Dental devices that are connected to the dental water system and that enter the patient's mouth (eg, handpieces, ultrasonic scalers or air/water syringes) should be operated to discharged water and air for a minimum of 20 to 30 seconds after each patient.