To dream that you are having some of the false teeth, means that someone will give you a hand when you will need it the most. You should rely on this person. If your teeth are rotten and looks disgusting, then it represents the disgusting side of your personality where you lied to someone or said the things that would make some situation favourable to you. If your teeth are falling out, it means that the bad things you said about others or did something awful to them made lots of damage and those people are suffering a lot. If you swallowed one of your rotten teeth, you will pay for your bad behaviour. To dream about healthy looking teeth, means that you will be the victim of other peoples lies. To get more detailed interpretation about your dream, you have to know which tooth has fallen out exactly, then the interpretation would better one.
Read more about dreaming of Teeth in other dream meanings interpretations.