Zac Efron shattered his jaw in 2013 after slipping and hitting his face on the corner of a granite fountain while running through his house in socks. He was knocked unconscious and when he came to again, his chin bone was "hanging off his face". He had to have his mouth wired shut and regularly went to physical therapy to rehabilitate his jaw. The injury caused his masseter muscles, which are the ones used for chewing, to overcompensate for the injured jaw muscles, leading to a noticeable change in his facial structure. Despite rumors that he had undergone plastic surgery, Zac Efron has denied having any type of cosmetic procedure and explained that his different-looking face was due to the jaw injury he sustained in 2013.