Both saline and silicone implants are FDA approved for cosmetic breast augmentation in the United States. Clinical trials demonstrate similar infection, failure and re-operation rates. Neither type of implant causes breast cancer. Despite lawsuits, and internet horror stories, medical studies do not link silicone implants to autoimmune disease like lupus, scleroderma or rheumatoid arthritis.
The major difference between saline and silicone implants is how the implants look and feel. In general silicone implants are softer, lighter and will feel more "natural." Saline implants are firmer, rounder and gives a more augmented or fake look. These can be positives or negatives depending upon your goals. The main downside to saline is increased scalloping and rippling, meaning a higher likelihood of seeing (visibility) or feeling (palpability) the implant in thin patients. The only two things that control implant visibility and palpability are the device itself and the amount, and quality, of tissue above the implant hiding it. Therefore, the type of implant selected plays a large role in your result in terms of both look and feel. The vast majority of my patients select silicone implants.
Interestingly, when we refer to silicone or saline, we are talking about the inner fill material. Both saline and silicone implants have the same silicone shell, so the body is exposed to the exact same material for the majority of woman who never experience a failure. Only if the shell was to fail would the breast pocket and capsule be exposed to the fill material. Saline is absorbed and urinated out, silicone gel remains inert, and except in extraordinary cases, stays within the breast pocket.
One factor that should not be considered when considering the difference between saline and silicone breast implants is price. A few hundred dollars is a small difference upfront, for a device you may have for decades. Additionally, both implants carry a lifetime warranty against device failure, but the silicone implant includes a 10-year warranty to help pay some of the surgery fees (up to $3500) should the device fail. To put it simply, both have a lifetime “parts” warranty and silicone includes a 10 year “labor” warranty while that “labor” portion of the warranty is an additional $200 for saline, thereby negating most of the price savings.