Breast implants are made of an outer layer of silicone and an inner part which is filled either with saline (salt water) or silicone gel. Other materials have been used in the past but silicone and saline have so far been shown to be effective and safe. The outer layer is made of a material called silicone elastomer, a material similar to rubber. This reduces the risk of leakage.

Saline has the advantage of not causing any problems if it leaks out into the body. However, saline-filled implants don’t have the natural feel of silicone-filled implants and give a less realistic reconstructed breast. They are more likely to leak or wrinkle than silicone implants and can make breast x-rays slightly more difficult to read.

Silicone implants are very commonly used in the UK. These are bags of silicone gel enclosed in a thin silicone shell. They are designed to feel soft and flexible, like a natural breast, and there are many different types. They can be tear-drop shaped or round, textured or smooth on the surface, and filled with either soft liquid silicone or, a more solid (cohesive) silicone gel. These days, most surgeons use cohesive gel implants.

A silicone gel filling gives a more natural feel to the breast than saline. If a silicone implant ruptures, surgery may be needed to remove the implant.

Like saline, silicone implants can appear cloudy on x-rays, making mammograms slightly more difficult to read. It's possible to get a good mammogram of a breast containing an implant, but you need to tell the radiographer that you have an implant.

One problem that may occur with a breast implant is capsular contracture. This is more likely to happen if you smoke, develop an infection, or have radiotherapy.

There have been concerns about possible health risks if silicone leaks from the implant. Over the years, silicone implants have developed and improved so that the risk of leakage has been greatly reduced. However, there will always be a very tiny amount of leakage.

Silicone implants have been successfully used for many years for breast enlargement.

In the past however, there were concerns that some women developed health problems as a result of having silicone implants. These problems included autoimmune illnesses (where the body has an inappropriate immune response to its own tissues) such as rheumatoid arthritis, connective tissue disease or even cancer. When this was looked into it was found that most problems were associated not with silicone implants, but with liquid silicone injected directly into the breast. Silicone injections are now banned in the UK and the US.

A lot of research in different countries has been carried out to see whether silicone implants cause health problems. No link has been found between silicone implants and the development of cancer or auto-immune illnesses. 

In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for ensuring the safety of breast implants. The Department of Health set up an Independent Review Group in 1997 to review their safety. They reported originally in 1998 and last met in 2004. They found no good evidence of an abnormal immune response to silicone and no evidence for a link with connective tissue disease. They therefore believe that there is no reason to stop using silicone implants. The full report is available on the MHRA website www.mhra.gov.uk

It is important to talk through any concerns with your breast care nurse, surgeon or a cancer support organisation before you have an implant.

All implants have a life span so will need to be changed after a number of years. Some last longer than others - the newer ones will last at least 10 to 15 years and probably longer.

If you have an implant you may need to have it changed if you:

• put on, or lose weight
• have a capsular contracture (formation of tough, fibrous tissue around the implant)
• have an infection.

It is very difficult to damage implants – normally only a severe chest injury would do this or something like a seatbelt injury from a car crash. So you can carry on with all your normal activities, including things like sports and air travel, without worrying that it will affect your implant.