Table 1 Factors related to aerosol contamination

Ultrasonic and sonic scalers

• They generate the highest rate of aerosols in a 6–12-in diameter from the operator.

• The application of high volume evacuators reduces airborne contamination by 95%.

Air polishing

• Airborne contamination of air polishing is almost equal to ultrasonic scalers.

• The application of high-volume evacuator and/or aerosol reduction device reduces airborne contaminations up to 95%.

Air-water syringe

• Airborne contamination of air-water syringes is almost equal to ultrasonic scalers.

• However, the application of high-volume evacuators can reduce airborne contamination by nearly 99%.

High speed air turbine handpiece

• An air-driven handpiece is powered by compressed air to spin the air-driven turbine.

• Air-driven handpieces reach speeds of up to 400,000 rpm in a variety of torques.

• The water flow speeds for turbines with one, two, and three coolant apertures are 42.38, 34.31, and 30.44 mL/min, respectively, or about 1.0 ml/s.

• High-speed dental handpieces without anti-retraction valves aspirate the debris and fluids and contaminate the air and water systems of the unit which may lead to cross-infection.

Slow speed handpieces

• The speed of their inbuilt motor can reach up to 80,000 rpm.

• The average pressure for air and external water in these handpieces are about 0.25–0.3 (Mpa) and 198 (Kpa), respectively.

• The average water flow in these handpieces is about 90–110 (min/ml).

Anti-retraction high-speed dental handpiece

• These handpieces reduce the microbial backflow into the tubes of the handpieces and dental units.

Electric motor handpieces

• Self-contained internal gearings in an electric motor handpiece enable it to function at a stable torque and speeds up to 200,000 rpm.

Tooth preparation with air abrasion

• Extensive microbial contamination with abrasive particles has been demonstrated.

Aerosol reduction device

• Aerosol reduction devices such as Jet Shield (DENTSPLY SIRONA INC., USA) can reduce the contamination up to 97% during air polishing.

Rubber dam

• Rubber dams minimize the formation of the blood- and saliva-contaminated aerosols.

• The application of rubber dam reduces airborne particles in ~ 1-meter diameter of the source of particle production by 70%.

High-volume evacuator

• High-volume evacuators can efficiently reduce the number of microorganisms, blood, and material released into the air.

• Since a small-bore saliva ejector is not an adequate substitute, when a four-handed operation is not an option, utilization of a high-volume evacuator attached to the instrument is necessary.

• The use of these types of evacuators when the utilization of a rubber dam is impractical can be highly beneficial.

•Researches indicated that the application of high-velocity evacuators with air polishers can reduce CFUs about 94.8%.

Ultraviolet radiation

• Ultra-violet radiation can be considered as a highly fungicidal, viricidal, and bactericidal agent via damaging DNA and denaturation of proteins.

• The International Ultraviolet Association (IUVA) stated that UV disinfection can reduce the transmission of the SARS-CoV-2 in air, water, and on surfaces.

Patient and dentist position

• The patient in the supine position enables the dental team to stay away from the patient’s breathing way.

Ventilation and air-conditioning system

• To reduce environmental contamination and prevent contaminated air circulation

Microbiological control of unit water system

• Periodic disinfection of the unit water system via application of chemicals and distilled water.

Preprocedural mouth-rinse

• The efficiency of chlorhexidine on SARS-CoV-2 has not yet been studied. However, the use of 1% hydrogen peroxide or 0.2% povidone-iodine is recommended.

• Prophylactic administration of mouthwash reduces the microbial load in the oral cavity.

Manual instruments

• Manual instruments are recommended to minimize the aerosol generation.