Turkish Journal of Biology




The objective of the present study was to investigate reduction in the colonization and growth of heterotrophic bacteria in dental unit waterlines by using hydrogen peroxide/colloidal silver as disinfectant. Twenty-seven dental units were included; 6 units that were more than 20 years old and 7 units that had been in use for 2 years comprised the old and new treatment groups, respectively. Fourteen units served as controls. The treatment groups were disinfected continuously and every 4 weeks shock doses were applied over a 20-week period. Water samples were taken before treatment, 1 and 2 weeks after treatment, and thereafter every 4 weeks; then they were inoculated onto R2A agar plates. While 1-16-week results for the old treatment group showed total heterotrophic bacterial counts of higher than 1 × 10^5 cfu/mL, at 20 weeks they were below 7.5 × 10^2 cfu/mL. Only 2 units were able to reach levels of Keywords: Biofilm, aerobic heterotrophic bacterial count, dental unit waterlines, hydrogen peroxide/colloidal silver

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