Comparative evaluation of the antibacterial effect of ultraviolet radiation on alginate and condensation silicone impressions compared to hypochlorite

Abstract

BACKGROUND: Dental impressions are a known potential vector for cross-contamination between patients and the dental laboratory. Effective disinfection is, therefore, a critical step in infection control protocols. This in vitro study aimed to evaluate and compare the antibacterial efficacy of ultraviolet (UV) radiation and 0.525 sodium hypochlorite solution for disinfecting two common impression materials: condensation silicone and alginate. MATERIALS AND METHODS: This in vitro study employed a comparative experimental design to evaluate disinfection efficacy. A total of 195 samples were utilized, comprising 90 discs each of condensation silicone and alginate, alongside positive and negative controls (n = 9 and n = 6, respectively). All samples were experimentally contaminated with standardized suspensions of three pathogenic species: Streptococcus pyogenes (beta-hemolytic Group A), Pseudomonas aeruginosa, and Staphylococcus aureus. The disinfection protocols consisted of either exposure to 0.525 sodium hypochlorite spray for 10 min or treatment with UV radiation using a dedicated device ("Fast Steril"). Antibacterial efficacy was quantitatively assessed by enumerating the mean colony-forming units (CFUs) postdisinfection. Statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney U-tests, with the significance level defined at alpha = 0.05. RESULTS: The analysis revealed a statistically significant difference in bacterial reduction based on the microbial species (P < 0.001). UV radiation demonstrated superior efficacy compared to sodium hypochlorite in disinfecting condensation silicone impressions (P < 0.05). Conversely, no significant difference was observed between the two disinfection methods for alginate impressions. Regarding bacterial susceptibility, the mean reduction in CFUs for S. pyogenes was significantly greater than for S. aureus and P. aeruginosa (P < 0.001), between which no significant difference was found (P = 1.0). CONCLUSION: Within the limitations of this study, UV radiation proved to be a more effective disinfection method for condensation silicone impressions than sodium hypochlorite spray. For alginate impressions, both methods were equally effective. Given its efficacy and the superior dimensional stability of UV-treated impressions reported in the literature, the adoption of UV radiation is recommended as a viable and efficient method for disinfecting both condensation silicone and alginate impressions, thereby mitigating the risk of cross-infection in dental practice.