The high-speed handpiece is a small, turbine-driven instrument used in dentistry for procedures like removing decay or shaping teeth. Operating at hundreds of thousands of revolutions per minute, this device generates aerosols, creating a mist of water, air, and patient material. Because it is exposed directly to the oral environment, the internal components become contaminated with biological fluids, including blood and saliva. Infection control protocols are necessary to ensure the safety of patients and dental staff by preventing the transmission of infectious agents.
Required Duration and Standard Protocol
The standard protocol for internal clearance occurs chairside immediately after a procedure. Dental organizations and manufacturers recommend flushing the internal air and water lines for 20 to 30 seconds between patients. This action must be performed with the handpiece detached from the patient and aimed into a sink or drainage receptacle.
Flushing uses the force of the unit’s water and air to physically remove debris from inside the lines. The water spray must be visibly streaming from the handpiece head during the entire 20-30 second interval to confirm effective clearing of the internal channels. This procedure must be performed for every patient as part of instrument reprocessing, ensuring gross contamination is expelled before the handpiece moves to sterilization.
Preventing Cross-Contamination Through Retraction
Flushing is necessary due to “retraction” or “suck-back,” which occurs when the handpiece stops. The handpiece uses air pressure to drive the turbine and water to cool the tooth surface. When the clinician stops the device, internal pressures rapidly change, creating a momentary negative pressure at the handpiece head.
This pressure drop draws oral fluids, such as saliva, blood, and aerosolized debris, from the patient’s mouth into the handpiece’s internal water and air lines. This contaminated material can be pulled back into the device’s tubing and potentially into the dental unit water system. Flushing with water or a specialized cleaner physically pushes this material out of the internal lumens. This mechanical clearing prevents cross-contamination of the water delivery system and exposure of the next patient to infectious biological material.
Flushing as One Step in the Reprocessing Cycle
The 20-30 second chairside flush is only the first step in a multi-stage infection control process; it does not result in a sterile instrument. Flushing is a form of pre-cleaning that must be followed by a complete reprocessing cycle. After the chairside flush, the handpiece is disconnected and transported to a designated decontamination area.
Subsequent mandatory steps include manually cleaning the external surfaces to remove visible debris, often using a soft brush and detergent. Following cleaning, the handpiece must be lubricated according to manufacturer instructions to protect internal components, particularly the bearings. The lubricated handpiece is then pouched and subjected to heat sterilization, typically via an autoclave, which uses pressurized steam to kill microbial life. Skipping the final heat sterilization step, even after a thorough flush, renders the device unsafe for reuse.