Abstract
OBJECTIVE: This study aims to determine the optimal disinfection frequency by comparing the effectiveness of different hydrogen peroxide (H(2)O(2)) shock treatment schedules in controlling contamination of dental unit waterlines (DUWLs). METHODS: Three dental units were randomly assigned to groups A, B, and C. After initial treatment with the Biofilm-Removing Set (BRS(®)), continuous treatment with 0.0141% H(2)O(2) was applied. Shock treatment with 1.41% H(2)O(2) was conducted every three weeks for group A, every 2 weeks for group B, and weekly for group C over 6 weeks. Water samples were collected thrice weekly to monitor bacterial counts, with a compliance threshold of 100 CFU/mL. Electron microscopy was used to assess biofilm morphology. RESULTS: A total of 132 samples were analyzed. Following BRS(®) treatment, bacterial counts decreased significantly to 15-45 CFU/mL. Groups B and C achieved 100% compliance, while group A had 68.42% compliance, with visible biofilm noted. There were significant statistical differences in compliance rates among three groups (p < 0.05). CONCLUSIONS: Continuous treatment with 0.0141% H(2)O(2), combined with biweekly or weekly 1.41% H(2)O(2) shock treatment, may help control DUWLs contamination in the short term under the conditions tested. Future studies should expand the sample size and duration for long-term efficacy assessment.