Zirconium Dioxide Nanoparticles Effect on the Color Stability of Maxillofacial Silicone after Outdoor Weathering

Background: Maxillofacial prostheses made of silicone elastomers tend to lose color. Despite advances in materials and processes, color change over time remains a challenge. Objective: This in vitro study aimed to observe how zirconium dioxide (ZrO2) nanoparticles impact the color stability of M511 heat temperature vulcanizing (HTV) silicone elastomer following outdoor weathering. Methods: ZrO2 nanoparticles were added in concentrations of 1%, 2%, and 3% by weight to the M511 HTV silicone elastomer. Brilliant red- and mocha-pigmented silicone pigments were utilized, along with colorless silicone as a base control. A total of 90 disk-shaped specimens were fabricated and divided into nine experimental groups, each containing ten samples (n = 10). All specimens were subjected to 6 months of outdoor weathering. A colorimeter was used to measure the values of L*a*b* according to the CIELab system. The 50:50% perceptibility threshold (Delta E* = 1.1) and acceptability threshold (Delta E* = 3.0) were used to interpret recorded color differences. At the 0.05 level of significance, the 1-way ANOVA and the Tukey post hoc test were used in the statistical analysis. Results: All evaluated specimen groups experienced a chromatic alteration (Delta E* > 0). The Delta E* values exceeded the perceptible threshold in all groups (1.1 units). The Delta E* value of the colorless group and the red pigment with and without ZrO2 nanoparticles were both above the acceptable threshold (p < 0.001). Mocha control was also above the acceptable level but was not statistically significant (p > 0.99). ZrO2 nanoparticles showed a reduction in color change. Conclusion: According to this in vitro study, all specimens underwent color changes. Even colorless silicone exhibited a significant color change. The red pigment showed a highly significant chromatic alteration. ZrO2 nanoparticles showed important protection and a reduction in color change. Its protecting action increased with an increase in the concentration of ZrO2 nanoparticles (3% ZrO2 > 2% ZrO2 > 1% ZrO2).