DEAR MAYO CLINIC: I recently heard something in the news about "gummy bear" implants. How are they different from other breast implants? Have they been approved by the FDA (Food and Drug Administration), and if not, do you think they eventually will be?

ANSWER: The medical term for the breast implants you heard about is "cohesive silicone gel implants." They're often called "gummy bear implants" because their consistency and texture is similar to those of the candy bears. The biggest difference between these new implants and others is that the gummy bear implants can be formed into and maintain a natural breast shape. Gummy bear implants are still under investigation, but preliminary study results look promising. It appears these new breast implants will be available to the general public in the United States soon.

Gummy bear implants are made from silicone. The major difference between these and other implants, however, is that the silicone particles in this new type of implant are more cross-linked, so the material hangs together -- much like a gummy bear. This change in the way the implants are made means they can be formed into a teardrop shape that mimics natural breast shape. Once implanted, they retain their shape. Because gummy bear implants are available in an extensive selection of sizes, they can be carefully chosen to match a woman's body shape and preference.

Saline breast implants and current silicone implants have no form stability. Although efforts have been made in the past to shape current implants like a teardrop, once they are implanted, and the surrounding tissue and skin puts pressure on them, they revert to a round shape.

In addition to looking more natural, preliminary research findings seem to indicate that gummy bear implants may have other advantages. Over the last six years, gummy bear implants have been studied in several clinical trials. Recently published data from those studies indicate that gummy bear implants appear to have a lower leak rate at six years than other implants. This finding is encouraging, although it's too soon to determine if the overall long-term leak rate is truly lower.

The research also showed that women who have gummy bear implants have a lower capsular contracture rate six years after the implants are placed. Capsular contracture occurs when fibrous scar tissue forms around the breast implant and then builds up and hardens over time. Capsular contracture can be painful and can distort breast appearance. Surgery is usually necessary to remove the excess scar tissue and often replace the implant.

One drawback that some women participating in the studies reported is that the gummy bear implants are slightly firmer than other implants. The reason is the cohesiveness of the implant material.

Gummy bear implants may well be a better alternative for women seeking breast augmentation, because they don't lose their shape when implanted. Surgeons also believe they will be beneficial to women who undergo reconstructive surgery after mastectomy.

Gummy bear implants have already been approved for general use in Europe and Canada. Based on the study results in the U.S. clinical trials, it seems likely they may be approved in this country, as well.

If you're interested in gummy bear breast implants, it's important to consult with a well-qualified surgeon who is board certified by the American Board of Plastic Surgery and has training and experience in breast reconstruction or augmentation. -- Galen Perdikis, M.D., Plastic Surgery, Mayo Clinic, Jacksonville, Fla.