YOU SAID:

You need to brush your teeth.

INTO JAPANESE

歯を磨く必要があります。

BACK INTO ENGLISH

I need to brush my teeth.

INTO JAPANESE

歯を磨かなければなりません。

BACK INTO ENGLISH

I have to brush my teeth.

INTO JAPANESE

歯を磨かなければなりません。

BACK INTO ENGLISH

I have to brush my teeth.