Effect of ultraviolet-protective 2-ethylhexyl salicylate incorporation on the mechanical properties of different maxillofacial silicone elastomers

Statement of problem. Whether the incorporation of ultraviolet-protective 2-ethylhexyl salicylate (UV-ES) affects the mechanical properties of different maxillofacial silicone elastomers, limiting the service life of facial prostheses, is unclear. Purpose. The purpose of this in vitro study was to examine the mechanical properties of different maxillofacial silicone elastomers incorporating different ratios of UV-ES. Material and methods. Three different ratios of UV-ES were incorporated into 3 different types of maxillofacial silicones (M511, TechSil-25, and A-2000), and the mechanical properties of the silicones were investigated. Silicone pigments were added to each silicone type to mimic skin color. Dumbbell-shaped specimens were fabricated for tensile strength, percentage elongation, and hardness measurements, and trouser-shaped specimens for tear strength measurement. A total of 240 specimens were prepared. UV-ES in 3 different ratios (1%, 2%, and 5%) and a control group of each silicone type were generated (n=10). The effects of maxillofacial silicone type and ultraviolet protective ratios on hardness, tensile strength, percentage elongation, and tear strength were examined by factorial ANOVA (alpha=.05). Results. The Shore-A hardness in the control and UV-ES added groups was not significantly different in M511 material (P>.05), and a statistically significant decrease was observed in all ratios in TechSil S25 and A-2000 silicones (P<.05). After adding 1%, 2%, and 5% UV protective into the silicones, the tensile strength and elongation of TechSil S-25 silicone material decreased significantly (P<.05), while these mechanical properties of M511 and A-2000 were not affected by UV-ES addition (P>.05). Tensile and tear strength values of the silicone elastomers were highest for TechSil S-25. Conclusions. The mechanical properties of M511 and A-2000 silicone elastomers were not adversely affected by the addition of 1%, 2%, or 5% UV-ES.