Bristol Palin's new look: Was it cosmetic surgery?

(CBS/AP) Did Bristol Palin have cosmetic surgery? The 20-year-old daughter of failed presidential candidate Sarah Palin says no way. She insists that her new face - thinner, with high cheekbones and a more angular jaw - is the result of surgery,  but not of the cosmetic sort.

She says she underwent corrective jaw surgery in December, one month after finishing third on "Dancing with the Stars."

"Yes, it improved the way I look, but this surgery was necessary for medical reasons," she told US magazine. "I wouldn't get plastic surgery unless I got in an accident or something terrible and got disfigured."

Palin said she had the operation so her jaw and teeth could align properly. While growing up, she wore braces and a device to help correct an overbite. But she said her dentist warned her that she'd have to have surgery one day.

Doctors call corrective jaw surgery orthognathic surgery and say it can help with several different problems, including difficulty chewing or biting food and swallowing. The surgery can also reduce chronic jaw pain and excessive tooth wear.

The surgery can take many forms, according to the American Association of Oral and Maxillofacial Surgeons. Bone tissue is often added, taken away, or reshaped - with screws, wires, and rubber bands used to keep the jaws in the new position. Incisions are usually made in the mouth so that scars are not visible.

Orthognathic surgery can dramatically enhance the patient's appearance. As for Palin, she told the magazine, "I look older, more mature and don't have as much of a chubby little baby face."