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Aerosols and splatter in dentistry
DENTAL AEROSOL AND SPLATTER
The terms “aerosol” and “splatter” in the dental environment were used by Micik and colleagues8, 9, 10, 11, 12 in their pioneering work on aerobiology. In these articles, aerosols were defined as particles less than 50 micrometers in diameter. Particles of this size are small enough to stay airborne for an extended period before they settle on environmental surfaces or enter the respiratory tract. The smaller particles of an aerosol (0.5 to 10 μm in diameter) have the potential to penetrate and lodge in the smaller passages of the lungs and are thought to carry the greatest potential for transmitting infections.
Splatter was defined by Micik and colleagues as airborne particles larger than 50 μm in diameter. Micik and colleagues stated that these particles behaved in a ballistic manner. This means that these particles or droplets are ejected forcibly from the operating site and arc in a trajectory similar to that of a bullet until they contact a surface or fall to the floor. These particles are too large to become suspended in the air and are airborne only briefly.
The consensus has been that the greatest airborne infection threat in dentistry comes from aerosols (particles less than 50 μm in diameter) due to their ability to stay airborne and potential to enter respiratory passages.13, 14 With the resurgence of TB, however, splatter droplets also must be considered a potential infection threat. The usual method for transmission of TB is through the formation of droplet nuclei.15 These form when a droplet of sputum or saliva containing Mycobacterium tuberculosis is projected from the patient by coughing or potentially by splatter from a dental procedure. As the droplet begins to evaporate, the size of the droplet becomes smaller, and it then has the potential to stay airborne or to become reairborne as a dust particle. Thus, splatter droplets also may be a potential source of infection in a dental treatment setting. Splatter and droplet nuclei also have been implicated in the transmission of diseases other than TB, such as SARS, measles and herpetic viruses. Some diseases known to be spread via an airborne route are listed in Table 1 .
|DISEASE||METHOD OF TRANSMISSION|
|Pneumonic Plague||Patient to patient without the usual insect vector (flea); apparently by inhalation of the causative bacteria|
|Tuberculosis||Droplet nuclei expelled from the patient by coughing; once considered an occupational disease for dentists|
|Influenza||Apparently associated with coughing but may require direct contact with the patient|
|Legionnaires' Disease||Aerosolization of Legionella pneumophila has been associated with air conditioning systems and hot tub spas|
|Severe Acute Respiratory Syndrome||Spread by direct contact and aerosolized droplets|
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Harrel, S. K., & Molinari, J. (2004). Aerosols and splatter in dentistry: a brief review of the literature and infection control implications. Journal of the American Dental Association (1939), 135(4), 429–437. https://doi.org/10.14219/jada.archive.2004.0207