Dental handpiece cause cross infection mainly in the following three ways:
1. Surface pollution caused by the contact of the patient's saliva, blood and spat during the operation of the handpiece in the oral cavity and internal pollution caused by the penetration of saliva and blood into the handpiece through the gap of the handpiece itself;
2. Air pollution caused by aerosols and droplets with pathogenic microorganisms entering the air when handpiece are cut by high-speed rotation;
3. The negative pressure formed when the high-speed turbine of the handpiece stops rotating can suck pathogenic microorganisms in the patient's mouth back to the inside of the handpiece, causing pollution.
