Controlling the porosity and density of silicone rubber prosthetic materials

The chemical components of the four silicone rubber polymers were reviewed. Methods of controlling the porosity and density of both the one-component semisolid prepolymer and the two-component fluid prepolymer systems were evaluated. The variables examined were deairing of the fluid systems; trial packing, pressure sealing, and processing of the semisolid materials; injection versus hand packing of the mold; the effects of moist-heat versus dry-heat application during processing; and the need for investment of the mold within the confines of a closed flask. It can be concluded that porosity of medical-grade silicone rubber polymers may be totally prevented, or accurately controlled, by proper handling techniques.