Many women are aware that implants can break down over time, requiring replacement just like car tires. Both saline implants, made out of a saltwater solution, and silicone implants, made out of gelatinous silicone, can form minute tears in their rubbery shells, causing ruptures. In the case of such defects that require product replacement, both manufacturers, Allergan Inc. and the Mentor Corporation, offer guarantees. Mentor has a 10-year guarantee to replace implants and defray some surgical fees; Allergan's warranty includes lifetime implant replacement and up to $1,200 for fees for the first 10 years.

Dr. Mark L. Jewell, a plastic surgeon in Eugene, Ore., who is a past president of the American Society for Aesthetic Plastic Surgery, said he warns his patients that breast augmentation surgery automatically guarantees a second operation at some future date. He added that many patients in clinical studies had elected to have follow-up operations to change implant type, size or position.

"Women are used to having their hair or nails done on a regular basis to maintain their appearance," said Dr. Jewell, who has conducted clinical trials for both implant manufacturers and is a consultant for Allergan, the manufacturer behind the ads running in Elle. "Ultimately, breast implants may also be a matter of maintenance."

But a rupture is only one of the local complications that may engender additional surgery. Like cocoons that grow around larvae, scar tissue can form around implants; and sometimes that scar capsule hardens and squeezes the implant, causing pain and deforming breasts. And saline implants can cause visible, tactile rippling beneath the skin.