Ultraviolet C as a method of disinfecting medical silicone used in facial prostheses: An in vitro study - Part 2

Statement of problem. Disinfection is an important factor in preserving facial prostheses and maintaining tissue health. However, whether disinfection with ultraviolet C is an effective disinfection method is unclear. Purpose. The purpose of this in vitro study was to evaluate the effectiveness of irradiation with different exposure durations of an ultraviolet-C light-emitting diode in the disinfection of the silicone (A-588-1; Factor II) used in facial prostheses. Material and methods. A total of 216 specimens were prepared, contaminated by multispecies biofilm, and divided into 9 groups (n=24) for different treatments: chlorhexidine 0.12% (G CHG), ultraviolet-C light-emitting diode for 5 minutes (G UVC5), ultraviolet-C light-emitting diode for 10 minutes (G UVC10), ultraviolet-C light-emitting diode for 20 minutes (G UVC20), their respective untreated controls (Gcontrol CHG, Gcontrol UVC5, Gcontrol UVC10, Gcontrol UVC20), and dimethyl sulfoxide (G DMSO) as the negative control. Cell viability was measured by using the methyl tetrazolium salt (MTT) method. Two statistical analyses were performed. First, a 2x3 ANOVA was carried out to compare the control groups (Gcontrol UVC5, Gcontrol UVC10, and Gcontrol UVC20) and the experimental groups of UV-C LED light with different exposure durations (G UVC5, G UVC10, and G UVC20). The second analysis was performed using generalized linear models to compare the optical density of the groups (G UVC5, G UVC10, G UVC20, G CHG, and G DMSO). Results. Cell viability results demonstrated a microbial reduction after exposure to the ultraviolet-C light-emitting diode for 20 minutes (G UVC20) compared with untreated controls (P<.05). The 5- and 10-minute exposures were statistically similar to their respective control groups (P>.05). The 20 minutes exposure had the lowest average optical density value, being statistically different from the 5-minute exposure (P<.05). A 20-minute exposure to the ultraviolet-C light-emitting diode (G UVC20) was similarly effective when compared with the standard disinfection treatment (G CHG) and dimethyl sulfoxide (G DMSO) (P>.05). Conclusions. Irradiation with an ultraviolet-C light-emitting diode for 20 minutes decreased the in vitro microbial cell viability on the medical silicone used in facial prostheses.