| 摘要 |
<p>A teeth-straightening device uses a pair of magnets which are fastened to the teeth so as to exert the required straightening force, which may be direct or torsional. With magnets, the force exerted increases as the teeth straighten; with other devices it decreases. The (pref. gold-plated) magnets may be bolted to metal bands fixed round the teeth, or to metal plates stuck to them with adhesive. The bolts are pref. square-headed, to keep the magnets from turning; alternatively, several bolts may be used. The force may be adjusted by partially short-circuiting the magnetic flux with a thin nickel plate.</p> |
