| 摘要 |
The system shown uses a band tightly fitted onto the tooth to be moved by a part turn about its longitudinal axis. There is an arch wire across the buccal face of the tooth, rigidly fixed. An elongated member of filament material, intermediate its ends, is of resilient tension spring structure. One end of said member is held fast to the band and is at least a part turn thereon wound in the direction the tooth is to be turned. With the spring in tensed condition, the other end of this member is held fast to the arch wire. As the spring contracts, the tooth will be turned in like manner as a top is started to spin upon withdrawal of its cord. The spring may be true helical, flattened helical or planar zig-zag.
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