The need to use aesthetic crowns after orthodontic correction, then it may lead to the phenomenon of insufficient blood supply to the teeth, so that the teeth appear obvious necrosis, a part of the patients after receiving orthodontic correction, the teeth will appear obvious loosening phenomenon, and may even appear black gums; orthodontic correction process, it will irritate the core of the teeth, causing the occurrence of periodontitis, and gradually develop into apical periapical inflammation. The tooth will hurt from then on, and if left alone, it can easily lead to endless pus.