Particle Size, Mass Concentration, and Microbiota in Dental Aerosols

Abstract

Many dental procedures are considered aerosol-generating procedures that may put the dental operator and patients at risk for cross-infection due to contamination from nasal secretions and saliva. This aerosol, depending on the size of the particles, may stay suspended in the air for hours. The primary objective of the study was to characterize the size and concentrations of particles emitted from 7 different dental procedures, as well as estimate the contribution of the nasal and salivary fluids of the patient to the microbiota in the emitted bioaerosol. This cross-sectional study was conducted in an open-concept dental clinic with multiple operators at the same time. Particle size characterization and mass and particle concentrations were done by using 2 direct reading instruments: Dust-Trak DRX (Model 8534) and optical particle sizer (Model 3330). Active bioaerosol sampling was done before and during procedures. Bayesian modeling (SourceTracker2) of long-reads of the 16S ribosomal DNA was used to estimate the contribution of the patients’ nasal and salivary fluids to the bioaerosol. Aerosols in most dental procedures were sub-PM1 dominant. Orthodontic debonding and denture adjustment consistently demonstrated more particles in the PM1, PM2.5, PM4, and PM10 ranges. The microbiota in bioaerosol samples were significantly different from saliva and nasal samples in both membership and abundance ( P < 0.05) but not different from preoperative ambient air samples. A median of 80.15% of operator exposure was attributable to sources other than the patients’ salivary or nasal fluids. Median operator’s exposure from patients’ fluids ranged from 1.45% to 2.75%. Corridor microbiota showed more patients’ nasal bioaerosols than oral bioaerosols. High-volume saliva ejector and saliva ejector were effective in reducing bioaerosol escape. Patient nasal and salivary fluids are minor contributors to the operator’s bioaerosol exposure, which has important implications for COVID-19. Control of bioaerosolization of nasal fluids warrants further investigation.

Aerosol concentrations and size distributions during clinical dental procedures

“…However, even though multiple procedures have been listed as AGPs, the current classification is mainly based on experimental studies, expectations, and observational studies. Recently, more research regarding aerosol generation in dentistry has been performed showing a potential for aerosol reduction with high-volume suction [ 2 , 3 , 4 , 5 ]. However, the number of studied patients has been low and there is still a clear lack of knowledge regarding the amount of generated aerosol in these procedures in real-life setting [ 6 , 7 ].…”

“…At the beginning of the COVID-19 pandemic the use of air turbine handpiece and ultrasonic scaler were prohibited in most countries as dental professionals were thought to be more prone to SARS-CoV-2 infection compared to other healthcare occupational groups [ 8 , 9 , 10 ]. However, contrary findings were published as the pandemic evolved and dental professionals had lower SARS-CoV-2 antibody levels compared to other healthcare professionals [ 11 ] and studies indicating dental procedures do not produce much aerosol particles size smaller than 10 μm if high-volume suction or external high-volume extraction device was properly used [ 2 , 3 , 4 , 5 ]. Additionally, personal protective equipment (PPE) in dentistry was improved when FFP-masks, face shields and hair covers were routinely recommended to use in the beginning of pandemic, and studies have been published indicating low numbers of work-related exposures in dental staff [ 12 , 13 ].…”

Evaluation of aerosols in a simulated orthodontic debanding procedure

“…This procedure is performed using high or slow-speed handpieces either with or without water. The debanding procedure has been shown to be aerosol generating [18][19][20][21][22] . Specifically, the use of high-speed handpieces has been shown to significantly increase the airborne particle concentration, but uncertainty remains on how the presence or absence of water during this procedure affects aerosol concentration 23 .…”