title: Reader's Forum.
authors: Department of Orthodontics, Sichuan University, Chengdu, China and Department of Orthodontics, Wuhan University, Hubei, China.
authors: Xiaoyan
authors: X
authors: Sun
authors: Department of Orthodontics, Sichuan University, Chengdu, China and Department of Orthodontics, Wuhan University, Hubei, China.
authors: Li
authors: L
authors: Xu