Evaluation of a hydrogen peroxide disinfectant for dental unit waterlines

Background. The purpose of this study was to investigate the use of a hydro gen peroxide-based dental unit waterline, or DUWL, treatment to reduce the colonization and growth-of heterotrophic bacteria. Methods. Twenty-three dental units with self-contained waters systems were randomly selected. Three of the units and tap water served as controls. Twe nty-four water samples were taken at baseline and once a week for five week s. They were serially diluted, spread-plated in duplicate onto R2A agar pla tes and incubated at 37 C for seven days. Results. At baseline, the tap water control had a mean count of 0 colony-fo rming units/milliliter, or CFU/mL, the three control DUWLs had a median cou nt of 8,440 CFU/mL. and the 20 treated DUWLs had a median count of 9,760 CF U/mL. By week 1, 19 (95 percent) of the 20 treated DUWLs had counts of less than 200 CFU/mL, and by week 4, the median count for all of the treated DU WLs was 0 CFU/mL. The measurement at week 5-showed that the reduction to be low 200 CFU/mL had been maintained. Scanning electron micrographs from proc essed DUWL tubing samples revealed a similar pattern of results,,with biofi lm accumulation more evident in the untreated control specimens. Conclusions. Following the parameters of this study, the, authors, used a h ydrogen peroxide-based disinfectant to achieve the, A goal of no more than 200 CFU of heterotrophic, mesophilic bacteria, per milliliter of unfiltered output water. Clinical Implications. An easy-to-use hydrogen peroxide based DUWL disinfec tant demonstrated effectiveness in improving the quality, of water used for intraoral procedures. Protocol compliance meets the ADA year 2000 goal.