You have to pay a registration fee every time you go. It's been almost a year now, and there are still 2500 yuan left. Doctors should do almost the same, unless you know someone, don't choose too much. I used to have to wait in line for a long time every time I saw the same doctor. I usually only watch it once a month. As for the damage to teeth, only dentists will understand. I looked up a lot of information on the internet before I did it and said it didn't hurt. It seems that orthodontics has been done abroad for a long time. However, tooth extraction must have an impact. Personally, I think dentists nowadays always like to extract teeth.