Retained dental root

• 保留牙根

Retained dental root的用法和样例：

例句

1. The root is covered with a hard material called cementum.
   牙根上覆盖着的坚硬材料叫作牙骨质。
2. In truth, both root development and the stimuli that initiate tooth eruption are complex and still little understood.
   事实上，牙根的发育以及让牙齿冒出的刺激都很复杂，目前知道得很少。