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

Abstract

Maxillofacial prostheses are frequently composed of silicone elastomers. The rough surface of the silicone material can lead to the accumulation of microorganisms, irritation of the surrounding soft tissue, and 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 the five experimental groups based on pigmentation, with 16 samples in each group. Colorless specimens were prepared without adding any pigments. The four study groups were prepared using different pigments (red, blue, yellow, and their mixture). Half of the specimens in each group were tested before aging, whereas the other half were tested after 750 h of artificial aging. The 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 two-way analysis of variance, independent sample t-test, and Tukey’s post hoc test, with p < 0.05 statistically significant. FTIR-ATR showed no differences between the pre- and post-aging groups, with similar peaks. Surface roughness significantly increased in the colorless, blue, and mixed pigment groups (p < 0.001). In contrast, surface roughness significantly decreased in the yellow and red pigment groups (p ≤ 0.001). Therefore, the induced aging considerably impacted the surface topography of the maxillofacial silicone. The pigment type and distribution in the silicone matrix affect the surface roughness. AFM analysis is a simple and straightforward method for assessing the surface roughness at the nanometer level.