rim expander

例句：

1. 1.The rim expander is used to widen the gap between the teeth.
   边缘扩张器用于扩大牙齿之间的间隙。
2. 2.During orthodontic treatment, the rim expander is used to gradually move the teeth into their correct position.
   在正畸治疗期间，边缘扩张器被用来逐渐将牙齿移动到正确的位置。
3. 3.The rim expander is an important tool in the process of aligning teeth.
   边缘扩张器是牙齿对齐过程中的一个重要工具。