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 α = 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.
Key Words: Cross‑infection, dental impression, disinfection, infection control, Pseudomonas aeruginosa, sodium hypochlorite, Staphylococcus aureus, Streptococcus pyogenes, ultraviolet rays

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 Arezoo Mazaheri: Pubmed,Google Scholar