After people noticed some drastic changes in Bristol Palin’s face, the 20 year old admitted to an operation—but says it wasn’t plastic surgery. Palin says she underwent corrective jaw surgery in December. "Yes, it improved the way I look, but this surgery was necessary for medical reasons,” she says in an upcoming issue of Us Weekly. She says she needed to realign her teeth and jaw but is pleased, anyway, with the surgery’s other results. "I look older, more mature and don't have as much of a chubby little baby face."