Survey of bacterial contamination rate of water in dental units of School of Dentistry, Shahed University

Microbial contamination of dental units is always a health problem in dentistry. This infection can be transmitted to patients. This study was done to evaluate the rate of bacterial contamination of water in dental unit of Shahed University, in particular by Escherichia coli (E. coli).
A total of 42 water samples from 7 dental units (endodontic, restorative, prosthetics, surgery, periodontics, implants and children) were taken. The sample was obtained from the tip of turbine. Also, seven samples from municipal water were taken as controls. For isolation and counting of total bacteria, blood agar medium and for E.coli isolation, EMB medium were used.
Gram positive bacilli were isolated most prevalently from samples, and Gram positive cocci and Gram-negative bacilli. E. coli contamination was not seen in any samples. The amount of total contamination was higher in the morning than in the afternoon and most contamination was seen in periodontics and surgery units.
In the present study, it was found out that the tip of turbines has a lot of pollution. Several ways are suggested for control of contamination. In this study, it was shown that the work by devices and leaving of water in the morning, before its use for the patient, can greatly reduce the microbial load.