| 摘要 |
<p>PURPOSE: To provide an orthodontic appliance capable of applying fixed load to teeth during the movement of teeth by using a shape memory alloy composed of specified nickel, titanium and copper. CONSTITUTION: In a shape memory alloy expressed by the formula, no-load stress is obtained by increasing the quantity of copper in the alloy, and the quantity of copper in the alloy is controlled to obtain desired physical mechanical characteristics. Accordingly, the quantity of copper in alloy composition is in the range of at least 3%, preferably 5%-11%, and this quantity gives an alloy composition having fixed load/no-load stress during a comparatively large range. Preferably, an orthodontic appliance is manufactured from a shape memory alloy where nickel, titanium and copper are mixed in such a manner as to have the maximum load stress equal to about 400Mpa or less and the minimum no-load stress equal to about 200Mpa or more.</p> |
