Monitoring of pollution conditions of the new dental unit waterlines

Objective To study changes of pollution conditions of the new dental unit waterlines. Methods By means of random sampling, 7 new dental chair units of the same brand were selected. Of which, 5 dental chair units (DCU) were supplied with water after centralized treatment of municipal water and 2 dental chair units were supplied with independent water storage tanks. From the first day of clinical use, water samples of three-way syringes and high-speed dental handpieces and mouthwashes were continuously collected for bacterial culture and the number of colonies was counted. Results A total of 343 water samples were collected. There was a statistically significant difference in the number of colonies in the water samples from the outlet of three-way syringes and high-speed dental handpieces after the waterlines was rinsed for 2 min before treatment (P 0.05) . Waterline washing could significantly reduce the number of colonies in the waterlines (P 0.05) . The number of colonies in the new DUWLs could exceed the recommended standard in the guideline on the second day of clinical use and the number of colonies increased significantly compared with that on the first day (P<0.05) . Conclusions In clinical work, no matter what kind of water supply method is used, in addition to waterline washing according to regulations, DUWLs should be disinfected daily. Key words: Microbial contamination; Colony; Dental chair unit