A dental aerosol is an
aerosol that is produced from
dental instrument,
dental handpieces, three-way syringes, and other high-speed instruments. These aerosols may remain suspended in the clinical environment.[1] Dental aerosols can pose risks to the
clinician, staff, and other patients. The heavier
particles (e.g., >50 µm) contained within the aerosols are likely to remain suspended in the air for relatively short period and settle quickly onto surfaces, however, the lighter
particles may remain suspended for longer periods and may travel some distance from the source.[2] These smaller particles are capable of becoming deposited in the
lungs when inhaled and provide a route of
diseases transmission.[3] Different dental instruments produce varying quantities of aerosol, and therefore are likely to pose differing risks of dispersing microbes from the mouth. Air turbine dental handpieces generally produce more aerosol, with electric micromotor handpieces producing less, although this depends on the configuration of water coolant used by the handpiece.[4][5]
Composition
These dental aerosols are
bioaerosols which may be contaminated with
bacteria,
fungi, and
viruses from the oral cavity,
skin, and the
water used in dental units.[6] Dental aerosols also have
micro-particles from dental burs, and silica particles which are one of the components of
dental filling materials like
dental composite.[7] Depending upon the procedure and site, the aerosol composition may change from patient to patient. Apart from
microorganisms, these aerosols may consist of particles from
saliva, gingival crevicular fluid,
blood,
dental plaque,
calculus, tooth debris, oronasal secretions, oil from dental handpieces, and
micro-particles from grinding of the
teeth and dental materials.[8] They may also consist of
abrasive particles that are expelled during
air abrasion and
polishing methods.[3]
Size
Dental aerosols contain a wide range of particles with the majority being less than 50 µm. The smaller particles with size between 0.5 and 10 µm are more likely to be inhaled and have the potential to transmit
infection.[3] Smaller particles are likely to remain suspended for longer periods of time, and may travel further from the source. Settling time of particles is described by
Stokes' law in part as a function of their aerodynamic diameter.
Potential hazards and mitigation
The
water used in the dental units may be contaminated with Legionella, and the aerosols produced by dental handpieces may contribute to the spread of the Legionella in the environment; there is therefore a risk of
inhalation by the
dentist, staff and patients.[9] The dental unit water lines (DUWLs) may also be
contaminated with other
bacteria like Mycobacterium spp and Pseudomonas aeruginosa.[10] Infection from Legionella species causes infections like
Legionellosis and several
pneumonia like diseases.[11] However, still there is no strong evidence that suggests the dentists are at greater occupational risk from Legionella.[9] Transmission of
tuberculosis also occurs from the
cough producing procedures on the patients with
tuberculosis that involve production of aerosols.[12]Mycobacterium tuberculosis is transmitted in the form of droplet nuclei which are smaller than 5 µm which stay suspended in the environment for longer duration. The development of active tuberculosis in Dental Health Care Workers (DHCWs) is less likely than the rest of the other Health Care Workers (HCWs). There are lacking evidences to prove the active tuberculosis development resulting from this transmission in Dental health care Workers (DHCWs).[13]
Dentists have previously been described as one of the top of the working groups with high risk of exposure to SARS-CoV-2. Due to the close proximity of the dental health care workers to the patients, dental procedures involving aerosol production is not advisable in patients who tested positive for COVID-19 except for emergency dental treatment.[17] On 16 March 2020, the
American Dental Association (
ADA) has advised dentists to postpone all elective procedures.[18]ADA also developed guidance specific to address dental services during the
COVID-19 pandemic.[19]
Elements like calcium, aluminium, silica and phosphorus can also be found in the dental aerosols produced during the procedures like debonding of orthodontic appliances.[20] These particles may range from 2 to 30 µm in diameter and there are chances of inhaling them.[21]
A number of methods have been proposed, and are widely used, to control dental aerosols and reduce risk of disease transmission. For example, dental aerosols can be controlled or reduced using dental suction,[22] rubber dam,[5] alternative handpieces,[2] and local exhaust ventilation (extra-oral suction).[23]
^King TB, Muzzin KB, Berry CW, Anders LM (January 1997). "The effectiveness of an aerosol reduction device for ultrasonic scalers". Journal of Periodontology. 68 (1): 45–9.
doi:
10.1902/jop.1997.68.1.45.
PMID9029451.
^Petti S (June 2016). "Tuberculosis: Occupational risk among dental healthcare workers and risk for infection among dental patients. A meta-narrative review". Journal of Dentistry. 49: 1–8.
doi:
10.1016/j.jdent.2016.04.003.
PMID27106547.
^Day CJ, Price R, Sandy JR, Ireland AJ (January 2008). "Inhalation of aerosols produced during the removal of fixed orthodontic appliances: a comparison of 4 enamel cleanup methods". American Journal of Orthodontics and Dentofacial Orthopedics. 133 (1): 11–7.
doi:
10.1016/j.ajodo.2006.01.049.
PMID18174065.
^Ireland AJ, Moreno T, Price R (December 2003). "Airborne particles produced during enamel cleanup after removal of orthodontic appliances". American Journal of Orthodontics and Dentofacial Orthopedics. 124 (6): 683–6.
doi:
10.1016/s0889-5406(03)00623-1.
PMID14666082.