Quantitative analysis of bacterial aerosols in two different dental clinic environments

Abstract

Microbial aerosols are generated during dental treatments and may represent an important source of infection. This study was designed to quantify bacterial air contamination during dental treatments in both a closed dental operatory and a multichair dental clinic. Air was sampled by using a slit type of biological air sampler. Following air sampling, blood- supplemented Trypticase soy agar plates were incubated at 37°C under anaerobic conditions for 7 days. The maximum levels of air contamination in the closed dental operatory were observed while dental treatments were being performed (four trials; 216 ± 75 CFU/m3 for ultrasonic scaling treatments and 75 ± 22 CFU/m3 for operative treatments). At 2 h after completion of the treatments, the bacterial counts were about the same as the pretreatment levels (12 to 14 CFU/m3). In the second part of the study, a multichair dental clinic was divided into four areas, and air contamination was monitored at each site. Three sites were located in active dental treatment areas, whereas no dental treatments were performed within an 11-m radius of the fourth site. At 3 h after the beginning of dental treatments, the highest bacterial counts were obtained in the three active dental treatment areas (76 to 114 CFU/m3). However, there was noticeable contamination in the inactive dental treatment area (42 CFU/m3). Thus, bacterial aerosols were able to spread into areas where there was no dental activity. My data show that dental treatments significantly increased the levels of bacterial air contamination in both a closed dental operatory and a multichair dental clinic. Whether such levels of contamination have any influence on infection rates is not known.