It's not necessary. This is required by the document. Children have studied hard for so many years, and you don't want to have a metal device in your mouth and an orthodontic device in your mouth because of this orthodontics.

or

That is, the correction has been completed, and there is a sticky lingual wire retainer inside the mouth.

Need to go to the provincial hospital to issue a certificate.

Security for the college entrance examination this year is very strict.