Appraisal of microbial contamination of dental unit water systems and practices of general dental practitioners for risk reduction.

The study aims to evaluate the microbial contamination in dental unit water system (DUWS) in Chandigarh, India, including knowledge, attitude, and practices of general dental practitioners (GDPs) to reduce the microbiological risks of DUWS. Microbiological risks were assessed by collecting water samples from 18 dental chair units including three main water supply units. Total of 44 water samples were examined for bacteriological contamination and the highest microbial contamination was observed in the ultrasound scalers having a range of 100 to 12,000 CFU/ml, with a median count of 950 CFU/ml. Only 2.3% of the water samples met the European Union recommendation of less than 100 CFU/ml, whereas 97.7% of the water samples have the total bacterial count exceeding 100 CFU/ml. In comparison to Center for Disease Control (CDC) guidelines, only 20.5% water samples fall within the recommended quality of drinking water (less than 500 CFU/ml), and the rest of the samples (79.5%) exceed the total bacteria count with a median count of 1100 CFU/ml. Acinetobacter species, Pseudomonas aeruginosa, and Sphingomonas paucimobilis were found in most of the water samples from DUWS. Dental chair units show higher microbial load and hence failed to meet any international guidelines, e.g., CDC. The highest microbial contamination was observed in ultrasound scaler and air/water syringe outlets. Hence, the study demand for Indian guidelines for the type of water used in DUWS water and urges for the proper training of GDPs to avoid further risks to the dental patients.