Understanding Breast Implant Anatomy

Both silicone and saline implants have an outer shell made of silicone-rubber material. But when someone refers to a "silicone breast implant," they mean the filler of the implant, not the shell.

The main components of breast implants include:

* the shell (the outside layer, sometimes called the envelope or lumen)
* the filler (inserted into the shell)
* the patch (covers the hole where the filler is inserted into the shell)

Typically the shell is made of a single layer ("single lumen"), but some implants have a double layer -- a shell within a shell ("double lumen").
Silicone Shells for Both Saline and Silicone Implants

Both silicone and saline implants have an outer shell made of silicone-rubber material. But when someone refers to a "silicone breast implant," they mean the filler of the implant, not the shell. The two types of implants used in the United States are

1. saline filled, silicone-rubber shell
2. silicone gel-filled, silicone-rubber shell

Currently, the use of silicone gel-filled implants is limited to patients requiring reconstructive or revision breast surgery.

Generally, the silicone-rubber shell is made of

* Cured long strands of silicones
* Approximately 20 percent finely powdered silica tightly bound to the silicone polymers
* Small amounts of other materials

Saline Filled Breast Implants

Saline implants are filled with a sterile saline solution -- the same type of salt water used in general surgery and for other internal purposes.

There are several types of saline-filled breast implants. These types vary depending on whether saline is prefilled before breast surgery or is filled during surgery, and whether the volume of the implant is adjustable.

Common saline implants:

1. Single lumen ("lumen" is the outside shell) -- prefilled at the factory to a fixed volume. There are no valves for filling during surgery or for adjusting after surgery.
2. Single lumen -- filled with a fixed volume of saline during surgery through a valve. After surgery there are no adjustments to the implant volume.
3. Single lumen -- filled during surgery. After surgery, the volume of the implant can be adjusted by adding or extracting saline through a valve in the implant.

Silicone Gel-Filled Breast Implants

The filler in silicone gel-filled breast implants is composed of silicone oil, cured large silicone, a small amount of uncured silicones, and other materials. Silicone is a very safe compound and has been widely used in a number of medical applications for many decades.

There are several types of silicone-filled breast implants:

1. Single lumen -- prefilled by the manufacturer to a specific volume of silicone gel.
2. Double lumen -- the inner lumen is prefilled by the manufacturer to a specific volume of silicone gel. The outer lumen is filled during the breast augmentation procedure with a fixed volume of silicone gel using a valve in the implant.
3. Double lumen -- the outer lumen is prefilled at the manufacturer with a fixed volume of silicone gel, while the inner lumen is filled during the procedure through a valve in the implant. This third type allows for adjustments to the filler volume after surgery.
4. The fourth type of silicone implant may appear to have no shell -- looks and feels like a semi-solid rubber gel.

Breast Implants other than Saline or Silicone

Alternative types of breast implants have a silicone rubber shell, but with a filler other than saline or silicone. Some use gel other than silicone gel. Other implants use an outer shell other than silicone rubber. None of these alternatives are approved in the United States.

Remember that breast augmentation is not permanent and breast implants do not last a lifetime. Eventually they may need to be removed and replaced with new implants. Data suggests that within ten years after surgery, up to 50 percent need to be replaced.

The durability and safety of today's implants are highly regulated by the FDA. Talk to a board-certified plastic surgeon about the best choice of implant for your breast augmentation.