Dr. Carey twisted the tooth a bit and racked it back and forth.

凯里医生转着圈儿的来回拉着那颗牙。

And then you take that bundle of fibers and you twist it a little bit, because by twisting it, you increase its breaking strength even more.

之后，再拿揉搓好的那根纤维捻一下，这样能让其抗断强度得到更大的提升。