In an effort to make implants more similar in feel to natural breast tissue, the gel used to make silicone breast prostheses is designed to be much thicker (more viscous) than water to mimic the density of a natural breast. Saline implants are supplied by the manufacturers as empty silicone shells filled with nothing but air; therefore, once the air is removed during surgery, they can be rolled up like a burrito and inserted through smaller incisions than if the implant was pre-filled. A fill tube is inserted into the implant port so that they can be filled after they are placed inside of the breast pocket. Silicone implants are supplied pre-filled to their full volume and cannot be adjusted; consequently they require a longer incision to be inserted.
Silicone Implant Ruptures
When silicone gel breast implants rupture, over 99% of the silicone stays inside of the breast scar capsule around the implant so the size of the breast changes very little, if at all. As a result, it can be hard to determine whether or not a silicone implant has ruptured by appearance alone. There are no completely reliable tests, such as mammograms, ultrasounds, CAT-scans or MRI’s to determine if a silicone gel implant is intact or not. An MRI is probably the most accurate test for detecting a rupture; they are not, however, perfect tests. An MRI can miss deflations and can be misread to report that an intact implant is supposedly ruptured.
Saline Implant Deflations
When saline implants rupture, all of the salt-water solution leaks out, is absorbed by the surrounding tissue and is eliminated. As the saline was sterile at the time of insertion, it is extremely rare for the fluid to cause a problem. Once the implant is completely deflated, this results in a considerable loss of breast volume, which demonstrates that the shell of the implant has lost its integrity. Therefore, it is normally very obvious when a saline implant has ruptured as the breast becomes much smaller in size and no special tests are necessary to make the diagnosis.
History of Silicone
Silicone gel implants made prior to 1991 had a much greater risk of capsular contracture, which is firm, hard scar tissue forming around the implant. This caused the breast to feel much harder than normal and possibly even a distorted appearance. The new silicone cohesive gel breast implants not only have a thicker outer shell to reduce leakage and deflation, but are also made of a thicker silicone gel than the first and second generation silicone implants. Therefore, there is considerably less leakage of silicone through the implant shell and the risk of a firm capsule forming is less frequent for the current generation of gel implants compared to those which were inserted before 1991.
Virtually all of these old implants leak silicone gel through their shells and it is generally recommended to have them removed and replaced with a better, more advanced implant.