Frequency Evaluation of Pseudomonas SPP Contamination in the Dental Unit Water Line System at Mashhad Dental School

Background and Aims : One of the well-known bacteria in dental unit water contamination is Pseudomonas aeruginosa.The aim of the present study was to evaluate the frequency of Pseudomonas aeruginosa species infection in the dental unit water samples of Dental Faculty of Mashhad University of Medical Sciences at 2018. Materials and Methods:In this Descriptive study, water samples collected randomly from the turbines of 10% of the active dental units in Mashhad Dental Faculty.Samples were collected at three time points including beginning of the day prior flushing, beginning of day after 2 min flushing, and middle of day after 20 sec flushing.Data analyzed with SPSS version 20 software using two-way ANOVA test and 95% of confidence interval.Results: All samples were infected at the first time point.At the beginning of the day prior flushing, the water contamination was higher than ADA standard in all departments except periodontology and operative dentistry.Water contamination decreased significantly after flushing at the beginning of day and middle of day measurements (P-value < 0.001).However, no significant difference was observed between beginning of day after flushing and middle of day samples. Conclusion:High bacterial frequency was found in dental unit water samples of Mashhad Dental Faculty regarding P. aeruginosa at beginning of the day.Flushing was an effective measure to reduce the bacterial frequency of dental unit water.