Quantitative microbial monitoring in a dental office

The aim of this study was to evaluate the environmental pollution before and after dental procedures (during one year) in a dental office in which a system of air filtration was effective and suitable procedures of microbial controls were routinely applied for instruments and small surfaces. The air contamination was evaluated during one year by the 'plate' method (Air Microbial Index, AMI) in each room of the dental office following a bimonthly monitoring program. Nutrient agar plates were exposed, in monitored areas for 1 h for each control time and incubated at 37 degrees C for 2 days. The number of viable cells was expressed as colony forming units per plate per hour (CFU/plate/h). During the observation year, the quantitative analysis of the microbiological levels in the operative areas was always within acceptable values. In fact, a range from 4-18 CFU/plate/h was found as the mean of AMI in each controlled room. In particular, the aerosol pollution following dental procedures did not significantly modify AMI values compared with AMI values recorded before dental procedures. Data presented here demonstrate that the combined use of effective infection control procedures and a system of air filtration can be efficacious in reducing airborne environmental contamination in a dental office and emphasise the use of an inexpensive method such as AMI to verify the environmental bacterial pollution.