Great! It goes the other way too.
For example, you have the word butikisto which means someone who works in a boutique or shop, or, simply put, a shopkeeper. To get to the word shop or boutique from there, you simply get rid of the profession ist part and you have butiko, which means a shop.
The Esperanto word for a dentist is the same as in English, except it has o in the end (like all nouns in Esperanto do).
First, guess how you would say a dentist, and then try to work out how you would reach the word for a tooth from there.