The 5 Generations of Silicon Breast Implants

Silicone implants are generally described in terms of five generations which segregates common characteristics of manufacturing techniques.

Wikipedia

First generation

The Cronin-Gerow implants were made of a silicone rubber envelope (or sac), filled with a thick, viscous silicone gel with a Dacron patch on the posterior shell.[12] They were firm and had a "teardrop" anatomic shape.

Second generation

In response to surgeons' requests for softer and more lifelike implants, breast implants were redesigned in the 1970s with thinner gel and thinner shells. These implants had a greater tendency to rupture and leak, or "bleed" silicone through the porous shell, and complications such as capsular contracture were also quite common. It was predominantly implants of this generation that were involved in the class action-lawsuits against Dow-Corning and other manufacturers in the early 1990s. Another development in the 1970s was a polyurethane foam coating on the implant shell which was effective in diminishing capsular contracture by causing an inflammatory reaction that discouraged formation of fibrous tissue around the capsule. These implants were later discontinued due to concern of potential carcinogenic breakdown products from the polyurethane.[13] A review of the risk for cancer from TDA by the FDA later concluded that the risk was so small so as not to justify removal of the devices. Polyurethane implants are still used in Europe and South America, but no manufacturer has sought FDA approval for sale in the United States.[14] Second-generation implants also included various "double lumen" designs. These implants were essentially a silicone implant inside a saline implant. The double lumen was an attempt to provide the cosmetic benefits of gel in the inside lumen, while the outside lumen contained saline and its volume could be adjusted after placement. The failure rate of these implants is higher than for single lumen implants due to their more complex design. The contemporary versions of these devices ("Becker Implants") are used primarily for breast reconstruction.

Third & Fourth generation

Third & fourth generation implants, from the mid 1980s, represented sequential advances in manufacturing principles and were elastomer-coated to decrease gel bleed, and a filled with thicker, more cohesive gel. These implants are sold under restricted conditions in the U.S. and Canada, and are widely used in other countries. The increased cohesion of the gel filler reduces leakage of the gel compared to earlier devices. A variety of both round and tapered anatomic shapes are available. Anatomic shaped implants are uniformly textured to reduce rotation, while round devices are available in smooth or textured surfaces.

Fifth generation

Evaluation of "gummy bear" or high-cohesive, form-stable implants is in preliminary stages in the United States but these implants have been used longer in other countries. Plastic surgeons believe that the greater gel cohesion in these implants is likely to significantly reduce the possibility of silicone migration. Early reports of these devices have shown significant improvements in safety and efficacy, over the older implants.