Effect of Nanosilica Filler Addition on Tear Strength and Intrinsic Pigment Stability of Facial Silicone Materials

In patients with facial tissue loss, facial prostheses restore aesthetics and function. Nevertheless, Room-Temperature-Vulcanized (RTV) silicones exhibit poor clinical performance, including low tear strength and color stability. Clean/industrial-grade RTV silicone is a cheaper substitute for medical-grade silicone. This study evaluated the effects of nanosilica fillers and inherent pigmentation on the tear strength and color stability of RTV silicone.

Fifty P25 silicone samples were used that contained nanosilica (0%, 1%, 2%, 3%, 6%) and TiO₂-impregnated Beauty by Lizzie Parra (BLP) foundation pigment. Tear strength was determined using a universal testing machine. Color stability was assessed under accelerated aging using the CIE Laboratory. Post hoc t-tests and one-way ANOVA were used (p < 0.05).

The tear strength was low, ranging from 18.984 kN/m (0%) to 6.446 kN/m (6%). The 2% nanosilica group was better than the 3% and 6% groups, as it remained clinically viable. The use of intrinsic pigments improved the color stability of the pigment/filler compared to controls. TiO2 and nanosilica were used to prevent UV and sebum discoloration.

The study highlighted trade-offs between mechanical integrity and esthetics, corroborated by the previous studies on silica-elastomer interactions. Limitations included small sample sizes and processing variables.

Mechanical durability of RTV silicone was enhanced by moderate 2 wt% nanosilica, whereas esthetics were maintained by intrinsic pigmentation. Optimization is suggested by filler surface modification and long-term clinical trials.