| 摘要 |
When an orthodontic appliance is to be attached to a portion which is hard to be seen from the outside and on the tongue side (rear side) of a tooth, a large step difference present between faces on the tongue side of adjacent teeth requires a wire bent in a complicated shape. However, since it has been found that a step difference between adjacent teeth is minute at a horizontal surface at the boundary between a dental crown and a root to permit drawing of a smooth envelope on them, a lingual straight arch wire having, in order for the wire to be arranged along the envelope, a planar shape consisting of a simple curve and straight lines smoothly connected to the opposite ends of the curve and existing inside a single horizontal plane, and a bracket in a shape suitable for the wire are available.
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