All synthetic implants used in modern breast enlargement surgery have a silicone elastomer shell. Saline breast implants are filled with sterile saline (salt water) solution and the silicone elastomer shell forms a tough, durable, elastic container for the saline solution. Silicone implants also have a silicone elastomer shell but they are filled with cohesive silicone gel. This is really tough and very durable.
Polyurethane breast implants are very similar to silicone implants except that an outer surface coating of polyurethane foam is bonded to the elastomer shell with a silicone adhesive. The polyurethane foam coating is around 1mm thick. They first became available in the 1970's.
So what are the advantages of polyurethane breast implants? Many cosmetic surgeons have found that women with polyurethane breast implants experience a considerably lower risk of having abnormally firm breasts. The main benefit is a significantly reduced risk of capsular contracture. Capsular contracture is one of the key causes of follow up revision surgery being required after breast enlargement. As part of its immune system, the human body encloses any foreign object in a fibrous capsule. This happens naturally with breast implants. In most cases, the capsule remains soft and isn't noticeable. However, in some cases, the capsule contracts to the extent that it becomes hard. It may cause discomfort and even pain. In some cases, the capsulated implant may need to be replaced through revision surgery.
Smooth coated breast implants can have capsular contracture rates of between 30% to 40%. However, breast implants covered in polyurethane foam can reduce capsular contracture rates down to rates between 1% and 10% measured over a period as long as 10 years. Even at 10%, this is significantly lower than that for smooth coated breast implants. Many silicone implants, without polyurethane coatings, have a textured surface. These too, have a significant effect upon reducing capsular contracture rates but their success in this has not been quite as strong as polyurethane implants.
Polyurethane is a very long chain molecule that appears to be harmless to the human body. It does not dissolve in body fluids and there is no evidence of it harming biological cells. Any non polymerised urethane molecules would be locked into the lattice of polyurethane. The body does, over time, break down polyurethane molecules into a substance known as TDA. There is no evidence to suggest that TDA is harmful to humans although studies and evidence are limited.
It is recommended that women with breast implants are scanned every two years. At present there is no evidence to proove that silicone or polyurethane breast implants are associated with an increased incidence of breasts cancer. There is also strong evidence to suggest that there is no elevated risk of women with implants developing breast cancer.
Women with implants should inform medical staff in advance when booking in for mammography so that the screening apparatus can be set up appropriately. Earlier mammography equipment struggled with implants and often made it more difficult for the mammogram technologist/radiologist to analyse the mammogram results. However, more recent advancements in technology have made mammography equipment more capable of coping with implants. It should be noted that there is no evidence to suggest that breast cancer is detected at a later stage through breast screening in women who have had breast enlargement surgery.