Currently, for cosmetic breast augmentation, saline filled breast implants are the only option available for women in the United States. These implants have a solid silicone shell filled with saline. In the event of leakage, the saline is simply absorbed by your body and your breast decreases in size. An inconvenience to deal with, but otherwise not much of an issue or controversy.
The FDA moratorium on silicone gel filled breast implants in 1992 was mostly due to controversy regarding what happened to the leaked silicone from these implants. There was concern that the silicone filler inside the silicone shell leaked out and caused systemic illness. This has since been proven not to be true.
As this controversy progressed, a new type of silicone breast implant was developed called the cohesive gel implant or “gummy bear” implant. These implants have been used around the world, except in the United States, since the mid-1990s. Cohesive gel breast implants are different because the silicone gel inside the implant is firmer than the silicone previously used. It is essentially a soft solid. If a cohesive implant is cut in half, there is no gross movement of the gel, and the implant maintains its shape. (Some microscopic diffusion of silicone will always occur through the shell.)
The advantages of cohesive gel breast implants are primarily that the implant maintains its shape in an upright position, which decreases the incidence of folding of the implant shell and the development of rippling. Less shell folding results in longer lasting implants. This also gives a more natural appearance to the breast. Further, leakage and breaking of the implants has been significantly minimized. Because there is no shell folding, the chances of the implant breaking are markedly diminished. Even if the outer silicone shell does rupture, the cohesive gel inside will not migrate anywhere. Early reports also indicate a lower rate of capsular contracture with cohesive gel implants.
Things are not all rosy, as there are some disadvantages to cohesive gel breast implants as well. First, the implants are more expensive than any others currently available. The surgical incisions will need to be larger than used for saline implants in order not to fracture or weaken the implants (gel fracture). Incisions for saline implants can be around 3 cm, whereas the incisions for silicone gel implants need to be around 5 cm in length. Because the implants are anatomically shaped, they need to be placed in the proper orientation and there is always a risk of rotation of the implants.