Study on Microbial Aerosols in Dental Practices

Dentists and their assistants are at a greater risk of exposure to Mycobacterium Tuberculosis than the general public, according to a recent study published in the British Dental Journal.

The risk of aerosol transmission of pathogenic agents during dental treatment is unknown. Dentists use high-energy equipment, such as drills and scalers, in the presence of bodily fluids such as blood and saliva, and dental plaque. This combination has been shown to generate aerosols of oral micro-organisms and blood.

A group of researchers conducted a study to measure the concentration of microbial aerosols in general dental practices and to use this information to carry out quantitative microbiological risk assessments.

Microbial air sampling was carried out continuously during 12 treatment sessions in 6 general dental practices in the South West of England.

Results of the Study

• The microbial aerosol concentration in treatment rooms was generally less than 10³ colony forming units per cubic metre of air (cfu.m^-3).
• In 6 out of the 12 visits, at least one peak concentration with much higher numbers of bacteria was detected.
• The peak concentrations were associated with increased recoveries of presumptive oral streptococci suggesting these aerosols originated from the mouths of patients.
• These aerosol peaks dissipated within 30 minutes and no dissemination into waiting areas was detected.
• The peak concentrations were associated with mechanical scaling procedures (47% of procedures giving rise to a peak) and to a lesser extent by cavity preparation (11%). No aerosolised blood was detected.

Thus, the researchers concluded that the data have been used to generate a framework for quantifying risk of exposure of staff to aerosolised microbial pathogens in general dental practice. For example, dentists and their assistants may have a slightly higher risk of exposure to Mycobacterium tuberculosis than the general public. The use of face seal masks that have been shown to protect against aerosolised micro-organisms may reduce this exposure.

Reference

Microbial aerosols in general dental practice by A M Bennett et. al published in the British Dental Journal.
https://doi.org/10.1038/sj.bdj.4800859