Bacterial Colonization of the Dental Unit Waterlines in Dentistry UQU Teaching Hospital, Makkah, Saudi Arabia

Background: The aim of the current study was to investigate bacterial colonization of the dental unit waterlines (DUWLs) in Umm Al-Qura University’s Dental Teaching Hospital in Makkah, Saudi Arabia. Methods: Eight dental units were selected to collect 48 water samples from DUWls, two samples from each water outlet of the dental unit (handpiece, air-water syringe, and cup-filler water). Each sample (300 ml) was treated with sodium thiosulfate (10 mg /100 ml) and then were filtered using 0.2 µm synthetic filter paper. The filter was then placed on 5% blood agar and incubated for 48 hours at 37 oC incubator. Results: The average number of heterotrophic plate count (HPC) bacteria in the water samples collected from the output of the 8 DUWLs was 57.79 colony-forming unit (CFU) per 300 ml water sample (0.19 CFU/ml). There were no statistically significant differences among CFU among the air/water syringe, the high-speed handpiece cooling water, or the cup filler water (p = 0.791). These findings were -within the acceptable limit according to Egyptian standards for drinking and domestic use of water. Conclusions: The current study has shown the level of CFU in DUWLs is acceptable in the dental care unit water system at Umm Al-Qura University’s dental teaching hospital.