StatementofProblem:Dental Unit Water Systems (DUWS) have been demonstrated to be contaminated with biofilms. This biofilm could be a site for growth and colonization of pathologic microorganisms.
Purpose: The aim of this research was to measure the Total Cultivable Flora (TCF) in DUWS of Khorasgan dental school and the effect of stabilized chlorine dioxide on its reduction.
Materials and Method: In this research, 60 samples of water from high speed turbines, air-water syringes, cavitrons and wash basins were collected. The samples were cultured in agar nutrition media and incubated for 5 days. After the incubation period, colonial counting was done by HPC method. In the next stage, stabilized chlorine dioxide was added in a container for each unit and the samples were taken from air-water syringes, cavitrons and turbine outlets. As for the first stage, after 5 days of culture and incubation, the samples were observed under microscope for counting the bacterial colonies. Kruskal-Walis and Mann-Whitney tests were used for statistical analysis.
Results: A high level of bacterial contamination (more than 200 CFU) was observed in high speed turbines, air-water syringes, cavitrons and wash basins. The highest colonial count was observed from cavitron and the lowest from washbasin outlets but the difference was not statistically significant. After using chlorine dioxide, the amount of bacterial colonies was significantly reduced ( p <0.05).
Conclusion: The amount of bacterial contamination in DUWS of Khorasgan dental school was higher than the accepted level. These bacteria were mainly opportunistic. The addition of an anti-bacterial agent in the DUWS will significantly reduce the bacterial count to an acceptable level.