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

Maxillofacial prostheses made of silicone elastomers tend to lose color. Despite advances in materials and processes, color change over time remains a challenge.

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.

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 (∆E* = 1.1) and acceptability threshold (∆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.

All evaluated specimen groups experienced a chromatic alteration (∆E* > 0). The ∆E* values exceeded the perceptible threshold in all groups (1.1 units). The ∆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.

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).