If you dreamed of having the bad teeth, then such dream warns you about upcoming disasters, problems, pain and suffering you will get. Probably you said something insulting to other people, therefore everything you did badly comes back to you. Consider the saying what goes around comes around, at this time of your life the saying is very suitable. The rotten teeth could also indicate the emotional state you are at the moment. Perhaps there are some thoughts which are unpleasant either.
Read more about dreaming of Teeth in other dream meanings interpretations.