Microbiological Assessment of Dental Unit Water Lines at a Tertiary Care Dental Teaching Hospital in Karachi

The dental practice depends on many factors, including the ample water supply through the plastic tubing system to irrigate the oral cavity's working area. It is used not only with dental materials but also to keep the machinery cool and evade the heat produced while working high-speed rotating instruments. The water is supplied by the tubing system known as the 'dental unit water lines' (DUWL). The main source of DUWL is usually the main supply of municipal water or the bottled water system. There is a high prevalence of microorganisms in this system, and limits have been set to control the spread of infection in dental settings. The formation of biofilm in the luminal surfaces of DUWL is another problem that can lead to the continuous growth of microorganisms inside DUWL. In this study, we assessed the samples of water collected from different dental units placed in different departments of tertiary care dental hospitals in Karachi to evaluate their conditions. The results showed the total viable plate count at 37ºC was positive for all samples. The mean total viable plate count (TVC) at 37° C was >200 colony forming units (CFU)/100 ml for all of the samples. The total coliform was found in 18 samples out of 38 (47.5%). Whereas fecal E. coli and fecal Enterococci/ Streptococci are not found in any sample, Pseudomonas species were found in all samples. The study concluded that strict disinfection practice is mandatory to avoid cross-infection in dental settings.