Dental unit water systems (DUWS) are used to irrigate the oral cavity and also used for various operative and endodontic procedures.  Water delivered from these devices is not sterile and has been shown to contain high numbers of bacteria. Biofilms accumulate on the inner surface of the tubing and it can be responsible for high levels of contamination of water delivered by DUWS that puts both the patient and the dentist at risk.

Aim: The purpose of the study is to evaluate the bacterial contamination of Dental unit water lines and compare the efficacy of three different disinfectants in eliminating the biofilms from DUWS to acceptable levels.

Materials and Methods: Nine dental units were used in the studies which were disinfected using three commercially available disinfectants Sterilex Ultra, Alkazyme W and Noni and randomly divided into three groups. Baseline water samples were collected before treatment and samples collected on day 1, 3, 7 respectively after treatment.Total of 108 samples were collected and subjected to microbiological analysis.

Results: The study results showed that untreated dental units were highly contaminated with multiple species of bacteria. Statistical analysis showed that bacterial reduction at the end of first day for all three disinfectants was statistically significant. Maximum disinfecting potential was achieved with Sterilex (97.7%).

Conclusion:It can be concluded that bacterial contamination of dental unit water lines in the untreated dental units used in this study exceededADA recommendations. Sterilex ultra can be used as Dental unit waterline disinfectant for a period of seven days, Alkazyme–W for a period of three days, Noni for one day effectively.