A centralised, automated dental hospital water quality and biofilm management system using neutral Ecasol™ maintains dental unit waterline output at better than potable quality: A 2-year longitudinal study

Abstract

Most studies addressing biofilm formation in dental chair unit waterlines (DUWLs) have focused on a range of individual dental chair units (DCUs) and no studies on a centralised approach in a large number of DCUs have been reported to date. Objectives To develop a centralised, automated water quality and biofilm management system serving the distribution network providing water to Dublin Dental Hospital's 103 DCUs, capable of maintaining DUWL supply and output water at better than potable quality standards in the long-term and requiring a minimum of human intervention. The potable water standard for the European Union does not specify an upper limit of aerobic heterotrophic bacteria, whereas a maximum of 100 cfu/mL is permitted in bottled water. Methods Mains water of varying quality was treated by specifically selected automated filtration units to provide DCUs with water of consistent chemical composition. This water was then automatically disinfected using an electrochemically activated solution Ecasol™ (Trustwater Group, Clonmel, Ireland) (2.5 ppm) prior to distribution to DCUs. Microbiological quality of both DUWL supply and output water was monitored weekly by culture on R2A agar for 10 sentinel DCUs for a 100-week period. DUWLs were tested for the presence of biofilm by electron microscopy. Results Chemical composition of processed mains water consistently bettered potable water standards. DUWL supply water and output water aerobic heterotrophic bacterial counts averaged <1 and 18.1 cfu/mL, respectively, from the 10 DCUs, compared to 88 cfu/mL for unprocessed mains water. This correlated with the absence of biofilm in DUWLs. No adverse effects due to Ecasol™ treatment of supply water were observed for DUWLs or DCU instruments. Conclusions This centralised and automated water treatment and biofilm management system consistently maintains DUWL output water at better than potable quality simultaneously in a large number of DCUs over the long-term.