Surface roughness of pigmented and non-pigmented maxillofacial silicone elastomer before and after artificial aging

Abstract

Maxillofacial prostheses are frequently made from silicone elastomer. The silicone material’s rough surface can lead to the accumulation of microorganisms, irritation of the surrounding soft tissue, and the progression of some microsites into mechanical failure and color deterioration. This in vitro study aimed to compare the surface roughness of M511 heat-vulcanized maxillofacial silicone before and after artificial aging. Eighty disk-shaped specimens were prepared and divided equally among five experimental groups based on pigmentation, with 16 samples in each group. The colorless specimens were prepared without adding any pigment. The four study groups were prepared using distinct pigments (red, blue, yellow, and their mixture). Half of the specimens in each group were tested before aging, while the other half was tested after 750 h of artificial aging. Surface roughness was measured using atomic force microscopy (AFM), and the silicone bonds and pigments were observed using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Data were compared between groups using a two-way analysis of variance, independent sample t-test, and Tukey’s post hoc test, considering a p < 0.05 statistically significant. FTIR-ATR showed no differences between the pre-and post-aging groups, with similar peaks observed. The surface roughness significantly increased in the colorless, blue, and mixed pigment groups (p < 0.001), surface roughness increased by 155.66%, 14.83%, and 96.12% respectively for colorless, blue pigment, and the mixture of pigments after 750 h of artificial aging. In contrast, the surface roughness significantly decreased in the yellow pigment (90.98%) and red pigment (5.7%) (p ≤ 0.001) after aging. The yellow pigment showed the smoothest surface after aging, while colorless specimens showed the roughest surface. Two-way ANOVA showed that pigment type and aging time significantly affected surface roughness. Therefore, induced aging considerably impacted the surface topography of maxillofacial silicone. The pigment type and distribution in the silicone matrix affected its surface roughness. The AFM analysis is a simple and straightforward method for assessing surface roughness at the nanometer level.