Breast implants are made of a silicone rubber shell filled with either silicone gel or sterile saltwater (saline). Every breast implant on the market uses a silicone elastomer as its outer shell, but the filling inside varies significantly depending on the type. Understanding these materials helps if you’re weighing your options or simply curious about what goes into these devices.
The Outer Shell: Silicone Elastomer
Regardless of what’s inside, the outer shell of every breast implant is made from medical-grade silicone rubber, also called silicone elastomer. This flexible, durable material is created by cross-linking silicone polymers into a solid but pliable form. The shell typically includes an inner barrier layer made of fluorosilicone or a modified elastomer coating, developed in the 1980s specifically to prevent the gel inside from slowly seeping through. Think of it like a balloon with a protective lining that keeps the contents locked in.
The shell’s outer surface comes in two varieties: smooth or textured. Textured surfaces are created through several manufacturing methods, including pressing salt crystals into the silicone (then dissolving them to leave behind tiny pits), gas diffusion, imprinting, or bonding a layer of polyurethane foam to the outside. Salt crystals ranging from 150 to 500 micrometers are used, depending on the desired texture. These surface differences affect how the implant interacts with surrounding tissue and aren’t something you’d feel from the outside.
Trace amounts of platinum remain in both the shell and the gel after manufacturing. Platinum-based compounds act as the catalyst that cures the silicone into its final form. The residual platinum is roughly 8 to 10 parts per million in the shell and about 0.9 parts per million in the gel. In a typical implant, that works out to around 281 micrograms total, with most of it sitting in the gel as inactive, elemental platinum.
Silicone Gel Implants
Silicone gel implants are filled with a material that feels similar to human fat. The gel itself is a lightly cross-linked silicone network swollen with silicone fluids. It starts as a two-part liquid system that cures through a platinum-catalyzed reaction at elevated temperatures, producing a sticky, cohesive mass. Manufacturers control the gel’s firmness by adjusting two things: how tightly the silicone molecules are cross-linked and how much fluid is mixed into the network.
Modern silicone implants are often called “cohesive gel” implants because the filling holds together rather than flowing freely like a liquid. If the shell were to rupture, the gel tends to stay in place rather than leaking out. This is a significant change from earlier generations of silicone implants, which contained a thinner, more liquid gel.
Form-Stable “Gummy Bear” Implants
Gummy bear implants take cohesive gel a step further. They use a more complex cross-linking structure that makes the gel firmer and more resistant to deformation. If you were to cut one in half, it would hold its shape, much like cutting a gummy bear candy. These implants have higher gel cohesivity, greater resistance to deformation, and absorb less energy when compressed compared to standard silicone gel implants. They’re typically shaped (teardrop rather than round) and paired with a thicker textured shell to prevent rotation inside the body. Different manufacturers achieve varying degrees of form stability depending on their specific gel formulations.
Saline Implants
Saline implants use the same silicone elastomer shell but are filled with sterile saltwater after being placed in the body. The saline follows pharmaceutical-grade standards: a 0.15 molar sodium chloride solution with a pH between 7.2 and 7.4. This is the same concentration as normal physiological saline used in IV bags and other medical applications. If a saline implant ruptures, the body simply absorbs the saltwater without harm, though the implant visibly deflates.
The main tradeoff is feel. Saline implants tend to feel less like natural breast tissue than silicone gel, and they’re more prone to visible rippling, especially in people with thinner tissue coverage.
Structured Saline Implants
A newer design called the IDEAL IMPLANT attempts to bridge the gap between saline’s safety profile and silicone’s natural feel. Instead of a single chamber, it uses two nested silicone elastomer shells creating an inner and outer compartment, each filled separately with saline through its own valve. Floating inside the outer compartment are one to three additional perforated baffle shells. These baffles have slits that allow saline to move through them slowly, restricting the sloshing that gives traditional saline implants their less natural feel.
Every component, the inner shell, outer shell, and baffle shells, is made from the same room-temperature-cured silicone material. The only filler is saline. So while the engineering is more complex, the actual materials are identical to what you’d find in a standard saline implant.
Lightweight Implants
One specialized option addresses a problem inherent to all traditional implants: weight. Standard implants weigh exactly as much as their size suggests, and that weight pulls on tissue over time. The B-Lite implant, developed in Israel, embeds tiny hollow borosilicate glass microspheres throughout a medical-grade silicone gel filler. These microspheres are chemically bonded to the gel network, creating a continuous, stable filling that weighs up to 30% less than a conventional silicone implant of the same size. The glass used is the same type found in laboratory glassware: chemically inert and high-purity.
How Materials Affect Your Experience
The material differences between implant types show up in a few practical ways. Silicone gel implants generally feel softer and more natural to the touch. Saline implants offer the reassurance that any rupture is immediately obvious (the implant goes flat) and the filler is harmless saltwater. Form-stable gummy bear implants hold a specific shape better over time but feel firmer than standard silicone gel.
All modern implants share a silicone elastomer shell with a barrier coating designed to minimize gel bleed. The shell is stronger than earlier generations, and the gels inside are more cohesive. What varies is the filling: standard silicone gel for a natural feel, highly cohesive gel for shape retention, saline for simplicity and easy rupture detection, or structured saline for a middle ground between the two.