It is assumed that it was rubbed onto the teeth using the fingers, as the toothstick - the forerunner to the toothbrush - was not in use at that time.

据猜测把手指当成牙棍（牙刷的前身，那个时候是没有牙刷的）将牙粉擦到牙齿上。

youdao

It is assumed that it was rubbed onto the teeth using the fingers, as the toothstick - the forerunner to the toothbrush - was not in use at that time.

据猜测把手指当成牙棍（牙刷的前身，那个时候是没有牙刷的）将牙粉擦到牙齿上。

youdao