Silicon is one of the most abundant elements on the earth.
Silica is a form of the element silicon and is most commonly encountered in nature in the form of sand.
Amorphous Silica - is used as a reinforcing agent to increase the tear resistance of silicone rubbers used in medical devices and implants.
Silicones are synthetically produced and are not therefore found naturally. Silicones are considered to be one of the most important materials used in medical implants and are found in the following forms fluids, gels, and rubbers (elastomers).
Silicone fluids or Silicone Oils are linear chains of polydimethylsiloxane (PDMS). Cyclic PDMS are important intermediates in the manufacture of the linear chain fluids. PDMS are virtually insoluble in water.
Silicone gels are a combination of lightly cross-linked polysiloxane networks and PDMS fluid. This combination produces a cohesive mass referred to as silicone gel. The combination of PDMS fluid and the cross-linked network is not a chemical bond. Instead the cross-linked network retains the PDMS fluid the same way water is retained in a sponge. As a result, there is a tendency for the fluid to bleed.
Silicone elastomers are extensively cross-linked and contain little free PDMS fluid. The barrier coating of breast implant shells is a special silicone elastomer which is selected specifically to minimize migration of PDMS fluid from the implants. The tensile strength and tear resistance of silicone elastomers may be increased by addition of amorphous silica which is usually pre-treated with organosilicon compounds to enable it to be tightly incorporated into the polymer network