Is the water in dental units clean?

Abstract

Objective To determine the microbiological quality of water from dental units in a general practice setting and current practice for disinfection of units. Design A cross-sectional study of the water quality from 40 dental units in 39 general practices and a questionnaire of the disinfection protocols used in those practices. Setting NHS practices in primary dental care. Subjects Thirty-nine general practices from the West of Scotland. Methods Water samples were collected on two separate occasions from dental units and analysed for microbiological quality by the total viable count (TVC) method. Water specimens were collected from the triple syringe, high speed outlet, cup filler and surgery tap. Each participating practitioner was asked to complete a questionnaire. Results Microbial contamination was highest from the high speed outlet followed by the triple syringe and cup filler. On average, the TVC counts from the high speed water lines at 37°C and for the high speed lines, triple syringe and cup filler at 22°C were significantly higher than that from the control tap water specimens. The study included units from 11 different manufacturers with ages ranging from under one year to over eight years. The age of the dental unit analysed did not appear to influence the level of microbial contamination. Five of the practices surveyed used disinfectants to clean the dental units but these had no significant effect on the microbiological quality of the water. The majority of dental units (25 out of 40) were never flushed with water between patients. A number of different non-sterile irrigants were used for surgical procedures. Conclusion The microbiological quality of water from dental units in general dental practice is poor compared to that from drinking water sources. Suitable sterile irrigants should be used for surgical procedures in dental practice. Further work is required for pragmatic decontamination regimens of dental unit water lines in a general dental practice setting