"Daant" is the word for tooth or teeth.
And "daanton" is used teeth along with some preposition like, daanton mein = in the teeth ; daanton se = with teeth ; daanton ko = to teeth ; daanton ka = of/belonging to teeth.
But for only one tooth, it's just daant mein, daant se, etc.,
The same goes for haath -> haathon ; pair -> pairon ; kaan -> kaanon
Hope this helps.