The envelope shells (which are also made of silicone) of the first generation of silicone gel implants were thick and sturdy but nevertheless had what was known as a gel “bleed” phenomenon – an extremely slow, very difficult to detect, infinitesimal weeping of fine silicone droplets from the surface of the implant. This weeping of silicone material through the envelope shell could lead to the forming of granulomas, cysts and excessive scar capsule tissue around the implant (called a “capsular contracture”), making the breast feel overall hard and stiff. Since their inception, saline implants have never had any “bleed” problem – the salt water volume stays within the implant shell, completely and indefinitely, unless there is an actual leak or rupture.
It took 20 years, but by 1983 a superior silicone implant silicone rainbow shell envelope had been perfected. It was thinner and softer for a better cosmetic look and feel but just as importantly, gel “bleed” was essentially eliminated. The granuloma/cyst rates and capsular contracture rates significantly decreased as expected accordingly.
In 1987, textured implant shell envelope surfaces were introduced. Independent and extensive research replicated at many centers over the next several years demonstrated that the textured surfaces significantly decreased capsular contracture and stiff scar rates even further. This was a significant advance for implant use in high risk for scar situations such as secondary breast reconstructions and revisions where the risk for capsular contracture problems is higher than normal.
The internal gel was reformulated into what is called a cohesive gel. This has become known as the “gummy bear” implant. This type of gel sticks to itself almost as if it were a solid, soft rubber material. It does not “ooze” or flow when squeezed. The previous internal gel material was more like a toothpaste. A leak in the implant meant the “toothpaste” oozed out, dispersing free flowing liquid silicone, intermixing it in with the surrounding breast tissues. This posed a very challenging aspect to the replacing of a ruptured silicone gel implant. From a practical point of view it was often a quite difficult and time consuming surgery to remove all the dispersed silicone in order to limit future granuloma and scar tissue formation. Many times this necessitated the removal of some healthy tissue hopelessly intermingled with silicone. Fortunately, we do not have to contend with these issues with the cohesive gel “gummy bear” implants because modern silicone gel does not ‘flow”. Although soft, mushy and mobile, if a gummy bear implant were cut completely in half, each silicone gel “wall” on either half would stay completely in place. The consequences of a rupture or leak of a silicone gel implant are now quite minimal. Replacement is still needed once a leak has been identified and implant integrity has been lost, but it is a much, much simpler process.
Silicone gel implants do not pose any risk to the developing fetus during pregnancy nor is infant breast feeding a concern – there is no risk to the baby. In fact, there are higher levels of silicone detectable in cow’s milk and infant formulas over the barely detectable levels in breast milk in women with implants!