Measurement of Airborne Bacteria and Endotoxin Generated During Dental Cleaning

Abstract

Dynamic dental instruments generate abundant aerosols in the work environment. Dental unit waterlines (DUWL) support a large microbial population and can be a significant source of bioaerosols generated during dental treatments. This study was conducted to characterize bioaerosol generation during dental treatments performed in standardized conditions. Culture-based method (R2A, and blood agar with and without O²) and fluorescence microscopy were used. Dental cleaning procedures were performed in an isolated treatment room with controlled ventilation rate. Andersen microbial samplers were used to collect culturable bioaerosols generated before (baseline), during, and after 2 hr of dental treatments. Inhalable dust samplers were used to measure total bioaerosols content in dental hygienist's and patients' breathing zones. AGI-30 were used for the collection of the endotoxin. The use of fluorescence microscopy in combination with culture demonstrated that dental staff and patients were exposed to up to 1.86 E+05 bacteria/m³ generated during treatments. Fortunately, bioaerosols returned to baseline within 2 hr after the dental procedures. The small diameter of the aerosols generated (<1 μm) suggests that the risk of contact between the aerosolized bacteria and the respiratory system of exposed individuals is likely to occur.

Keywords:

• airborne bacteria
• air sampling
• dental bioaerosols
• endotoxin
• personal exposure
• waterborne bacteria

ACKNOWLEDGMENTS

The authors gratefully acknowledge the active collaboration of Gaetane Houde (dental cleaning treatments); Eric Lacoste and Robert Bouclin (dental examinations); Marcel Proulx (medical supervision); Serge Simard (statistical analyses); and Daniel Grenier for the treatment room access and for his advice during this work. The authors thank Annie Leduc and Marie-Chantale de Latrémoille for technical support. This work was supported by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). Steve Dutil was supported by an FRSQ and IRSST studentship. Caroline Duchaine acknowledges new investigator IRSST-CIHR and FRSQ Junior 2 scholarships.

Notes

^AAnaerobic chamber was used.

^ACulture count = CFU/mL and FM count = bacteria/mL.

^BRecovery = culture count/FM count × 100.

^CN/A = not applicable.

^AN/A = not applicable.