In the Tractate Brachot of the Babylonian Talmud it states that a dream where your front and back teeth fall out portends that your children will die.

This has to be taken in the context of that particular passage of the Talmud which is discussing dreams and their interpretation. In this context there are two important things to note:

  1. That dreams are meant to displace punishment, ie. in a dream you live through the horror of the experience so that you don't have to be punished in the waking world.
  2. After the age of 22, good dreams are actually bad omens, and you are expected to have only bad dreams.
The Talmud also mentions here that one who doesn't experience any bad dreams over more than two years is in dire straights because it signifies that God is no longer punishing you in this world but is reserving your punishment till after you die. (The Midrash(I think, though I cannot recall the source) discusses how Abraham chose to have his descendants suffer for 400 years in this world because the sum total of that suffering would be less than one moments' suffering if the punishment was administered in the afterlife.)