There are two main types of implants available for breast augmentation in the United States:

• Saline implants. The most common type of breast implant approved for commercial use in the United States. Saline implants are filled with a sterile saline solution (saltwater). If these implants should leak or rupture, the solution is absorbed by the body. Saline implants have not been associated with any risks of disease. They are approved for use for breast augmentation surgery in women aged 18 years or older, and for breast reconstruction in patients of any age.
• Silicone implants. These implants are filled with silicone gel. In the past several years, there has been controversy regarding the safety of silicone implants, which were believed to be associated with connective tissue diseases and autoimmune diseases. Although they were available in the United States beginning in 1962, the Food and Drug Administration (FDA) withdrew silicone implants from the market in 1992 with the exception of use in clinical trials.
  
  But to date, all subsequent studies have failed to show any increased risk of connective tissue diseases and autoimmune diseases among women who have chosen to have silicone implants, and some patients claim that silicone implants feel more natural than their saline counterparts. As a result, the FDA lifted its restrictions on silicone implants last year, allowing their use for breast augmentation in patients 22 years or older, and for breast reconstruction surgery in patients of any age. Even though many other countries have not removed silicone implants from the marketplace, the FDA is requiring companies that manufacture silicone implants to continue conducting long-term studies on their safety and efficacy.

There are a number of other variations among implants to accommodate individual circumstances and preferences. These variations include:

• Shell surface type (smooth vs. textured)
• Size (volume contained in the implants)
• Shell thickness (also referred to as the envelope or lumen)
• Fill design varieties (for saline implants)
  
  
• A fixed volume prefilled by the manufacturer
• A volume that can be filled during the operation through a valve
• A volume that is filled after the operation
• Shape (round or contoured)
• Profile (how far it projects forward)