The Effect of Dental Unit Waterline Flushing on the Quality of Water in Dental Teaching Center in Malaysia

Abstract

The aim of this study to assess the efficiency of flushing method of Dental Unit Waterline (DUWL) system in reducing the number of microorganism. Water samples were taken before and after two minutes of flushing from air-water syringes system in ten randomly selected dental units in a Dental Teaching Centre. These samples were immediately transferred to the microbiology laboratory in the cool box within 8 hours for the heterotrophic plate count (HPC) test. Paired t-test was used to analyse number of microbe before and after flushing. The numbers of colony forming unit (CFU) ranged from 13,000 to 120,000CFU/ml in unflushed samples, and 3,000 to 15,000CFU/ml in flushed samples. The mean HPC post-flushing was lower than pre-flushing [8360.00 (4561.48) vs 63300.00 (44587.12) CFU/ml]. The mean HPC between pre- and post-flushing was significantly different (P=0.004, 95% CI 22039.52, 87840.48). The coliform count from the control was 140 CFU/ml. In conclusion, flushing method of DUWL system significantly reduces the number of microorganisms in the dental unit. However, the level of microorganisms still does not meet the standard guideline by Environmental Protection Agency for safe drinking water, which should be below 500 CFU/ml. In our opinion, the duration of flushing should be increased and additional chemical treatments of the dental units should be implemented to ensure the safety of patients and dental personnel.