noun
lingual braces
Dental term for braces attached to the back (tongue side) of the teeth, as opposed to the front (labial) side.
裏側矯正は、装置が目立たないので人気があります。
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).