An orthodontist is a dentist whose special job is to help teeth grow straight when they have not been growing correctly. They fit braces, check how the bite meets, and plan slow changes over months or years. They are still a kind of dentist, but extra-trained for this one problem; your family dentist may send you to them. The word is used in clinics and insurance talk. In casual speech people often just say “the braces doctor,” which students already understand — orthodontist is the precise job title.

齒顎矯正醫師（口語也說矯正醫師）