During a random kitchen discussion with a guest (German), we discovered that both in German and in Finnish, the first set of teeth is called "milk teeth" (Milchzähne, maitohampaat).
But the second set has a way cooler name in Finnish: they're called "iron teeth" (rautahampaat). In German they are boringly "bleibende Zähne", and in English, correspondingly, permanent teeth.
The English Wikipedia calls the first set of teeth "primary teeth", but "milk teeth" gives some Google hits, too. Some dictionaries claim it is a metaphor for "period of infancy". Maybe the native English speaker blog readers can tune in and tell what "milk teeth" usually means, if anything.