Jeremy Laurance: Learning to live with a new look

It is three-and-a-half years since the world's first face transplant was carried out on Isabelle Dinoire, 41, who received the lips and chin of a dead woman, as well as part of her nose and cheeks, after being mauled by her dog in northern France.

Half a dozen similar operations have been carried out since but the radical surgery is far from being an established treatment for facial disfigurement.

Ms Dinoire, one of the few transplant patients who has agreed to be identified like Connie Culp, has spoken movingly about the difficulty of coming to terms with her new face following the transplant in November 2005.

"The hardest thing to accept was to have the inside of someone else's mouth. It wasn't mine, it was all soft, it was atrocious," she said.

On one occasion she described finding a hair growing from her chin where none had been before. She said she thought of her donor as a twin to whom she used to speak out loud in the early months after the operation. "You can see that [the hair] is yours, but at the same time that she is there. I am keeping her alive," she said.

She expressed the difficulty of learning to live with a new identity. "Before the operation, I expected my new face would look like me but it turned out that it was half me and half her. It takes an awful lot of time to get used to someone else's face."

The operation is controversial because it is cosmetic rather than life-saving, as in transplants of vital organs such as the heart or kidneys. There is the risk of complications and recipients must take immunosuppressant drugs for the rest of their lives which increase the risk of cancer.

Against that, face transplant pioneers argue that people who are grossly disfigured are forced to hide themselves away and are unable to live a productive and high quality life in a society that judges people by their appearance.

The world's second face transplant was carried out by surgeons in China in 2006 on a farmer, Li Guoxing, who had the entire right side of his face torn off by a black bear in 2003. Doctors gave Mr Li, 30, a new nose, upper lip, cheek and eyebrow.

After a few months, he could eat, drink and talk and returned home. But he suffered multiple instances of rejection, and died, apparently of an infection, in 2008.

The most recent face transplant was carried out in France on a 30-year-old burns victim who received two new hands at the same time. French surgeons have performed four of the seven face transplants carried out around the world.