lingual braces
Dental term for braces attached to the back (tongue side) of the teeth, as opposed to the front (labial) side.
Lingual braces are popular because the appliance is not noticeable.
Refers to labial (front-side) braces, the more common type; 裏側矯正 is the opposite, placed on the inner side.
Compound of 裏側 (back side) and 矯正 (correction, orthodontics).