Objective: To investigate the efficacy of Sterisil silver ion based products in controlling heterotrophic bacteria of dental unit waterlines (DUWLs) in multiple dental offices over four-year period. Material and Methods: The four silver ion based products tested were manufactured by Sterisil Inc. (Palmer Lake, CO) for controlling microbial contamination of DUWLs: PureTube and Citrisil tablets were designed for bottle systems; PureTube Plus for municipal water; and PureLine for multiple dental units. A total of 264 samples of DUWLs were collected from 28 dental offices. The standard method 9215D of the American Public Health Association was used for determining the heterotrophic plate count (HPC) by using the membrane filtration technique, R2A agar and incubation for seven days at 22oC. Results: Among the 54 samples treated with PureTube, 98.1% met the CDC guidelines of ≤500 CFU/mL. For the samples treated with PureTube Plus, 52 of 53 had ≤100 CFU/mL; only one exceeded 500 CFU/mL and required an additional shock treatment. The PureLine and Citrisil tablet group contained 117 and 40 samples, respectively; both products eradicated 100% of HPC.
Treatment | N | Heterotrophic Plate Counts (CFU/mL) | % Pass Rates (<500) | |||
≤10 | 10 - ≤100 | 100 - ≤500 | >500 | |||
PureTube | 54 | 45 | 8 | 2 | 1 | 98.1% |
PureTube Plus | 53 | 46 | 6 | 0 | 1 | 98.1% |
PureLine | 117 | 115 | 2 | 0 | 0 | 100.0% |
Citrisil tablet | 40 | 36 | 4 | 0 | 0 | 100.0% |
Total samples | 264 | 242 | 20 | 2 | 2 | 99.2% |
% of Total |
| 91.7% | 7.6% | 0.8% | 0.8% |
|
Conclusions: The data demonstrate that all four Sterisil's products perform equally well, exceeding the standards established by the CDC and ADA for dental water quality. To maximize the benefits of silver based products, adequate shock treatment is essential to control existing biofilm in DUWLs. Partially supported by Sterisil Inc.