Suitability of Room‐Temperature Vulcanized Silicone Elastomer for Maxillofacial Prostheses in the Indian Climate: Formulation, Properties and Cytocompatibility

ABSTRACT

Globally, millions of individuals suffer from facial defects due to congenital anomalies, or trauma. Maxillofacial prosthetics use tissue‐like synthetic materials to restore facial form and function. However, performance of these materials is highly influenced by climate conditions, creating a critical need for prosthesis materials tailored to specific environmental conditions. In this study, we developed soft room‐temperature vulcanizing (RTV) silicone based elastomeric materials for maxillofacial prosthetic applications, with particular emphasize on suitability for the Indian climate. Prosthetic materials were prepared at room temperature using a unidirectional vacuum mixing process at −890 mbar, with mixing speed 300–400 rpm and mixing time 10 min. A systematic formulation strategy based on design of experiments (DOE) was employed, wherein the weight ratio of crosslinker to base elastomer, silica filler and UV absorber were systematically varied. Initially, 25 formulations were developed according to the DOE, and preliminary evaluated for tensile strength, tear strength and hardness. Based on these results 5 optimized formulations were selected for detailed analysis of structural characteristics, thermal stability, filler‐induced microstructures, water sorption behavior, surface hydrophobicity, mechanical properties and cytocompatibility. The optimized RTV specimens exhibited tear strength of ~11.7–14.6 N/mm, tensile strength of ~2.8–5.5 MPa, Shore A hardness below 40, surface hydrophobicity with contact angle ~100°, very low water sorption (~0.1%–0.3% up to 240 h) and excellent cytocompatibility. In vitro cytocompatibility studies revealed high cell viability, suggesting that the developed RTV specimens effectively support cell survival and exhibit excellent cytocompatibility. To evaluate the suitability for the Indian climate, specimens were subjected to 3 and 6 months of natural weathering. After 6 months, the developed RTV formulations showed ~10%–15% increase in tensile strength, tear strength and Shore A hardness, whereas, the control formulation (without UV stabilizer and other additives), showed ~25%–30%, increase along with noticeable color change. These findings demonstrate the improved weathering stability of the developed formulations under Indian climate conditions. Finally, a prosthetic ear was successfully fabricated using an in‐house customized mould which demonstrates the practical applicability and suitability of the developed formulation.