Oral therapy is prone to aerosol propagation because of its treatment space and the particularity of the equipment .First，dental treatment with high-speed turbo cell phone,ultrasonic cleaning machine,ultrasonic bone knife,three-use gun and other water mist miexd with the patiern’s blood and saliva,easy to creat aerosols,pollution of the surrounding air and object suface;Secondly,it is easy to cause patients to cough or even  vomit during oral treatment,which is also one of the risk factors aersols.Bacteria and viruses are known to be transmitted by aerosols.

In addition the virus may be through aerosol transmission into the same clinic to patients or health care workers while in oral treatment,resulting in cross-infection.Even because aerosols will be sus-pended in the air for a period of time,may remain on the surface of the dental chair and dental instru-ments,and are repeatedly inhaled by the patient or health care provider of subsequent visits,resulting in indirect cross-infection.