Evaluation of the bacterial contamination of air and surfaces in different dental environments

Aim: In dental clinic environment, dental staff and patients are daily exposed to many types of infectious agents transported by aerosols and droplets, promoting an increased risk of cross infection. The aim of this study was to assess the level of bacterial contamination of air and surfaces in different wards of the educational clinic in Arak University of Medical Sciences. Materials and Methods: Samples were obtained from the air and surfaces of five active wards of the dental school clinic. Air sampling was performed actively at ½ and 2 m distances from two random units in each ward. Sampling from surfaces was conducted using a wet sterile swab from the washing sink and handpiece after disinfection. Grown colonies were counted and bacterial phenotyping was based primarily on morphology, Gram-staining, endospore formation, catalase activity, and cytochrome oxidase presence. For statistical analysis, the Kruskal–Wallis test was used at a significance level of P < 0.05. Results: Bacterial contamination was detected in all of 80 samples taken from the surfaces of different sections. Regarding the total number of colonies growing from surface samples, there was no significant difference between the studied wards (P > 0.05). The mean concentration of airborne bacteria in the pediatric ward (488 CFU/m³) at a distance of 0.5 m and the surgical ward (339 CFU/m³) at a distance of 2 m had the highest value compared to other wards. In general, there was no statistically significant difference between the total density of airborne bacteria at distances of 0.5 and 2 m (P > 0.05). Conclusion: Bacterial contamination in the environment of the dentistry clinic increases during the treatment process. The clinic's space, the types of the ward and treatment process, and distance from the unit are among the factors affecting the type and diffusion extent of microbial aerosols.