Biomechanical characterization of a low density silicone elastomer filled with hollow microspheres for maxillofacial prostheses.

An ideal material for maxillofacial prostheses has not been found. We created a novel material: silicone elastomer filled with hollow microspheres and characterized its biomechanical properties. Expancel hollow microspheres were mixed with MDX4-4210 silicone elastomer using Q7-9180 silicone fluid as diluent. The volume fractions of microspheres were 0, 5, 15, and 30% v/v (volume ratio to the total volume of MDX4-4210 and microspheres). The microspheres dispersed well in the matrix. The physical properties and biocompatibility of the composites were examined. Shock absorption was the greatest by the 5% v/v composite, and decreased with increasing concentrations of microspheres. The density, thermal conductivity, Shore A hardness, tear and tensile strength decreased with increasing concentrations of microspheres, while elongation at break increased. Importantly, the tear strength of all composites was markedly lower than that of pure silicone elastomer. Cell viability assays indicated that the composite was of good biocompatibility. The composite with a volume fraction of 5% exhibited the optimal properties for use as a maxillofacial prosthesis, though its tear strength was markedly lower than that of silicone elastomer. In conclusion, we developed a novel light and soft material with good flexibility and biocompatibility, which holds a promising prospect for clinical application as maxillofacial prosthesis.