Every dream has a meaning of some sort. I know it by experience. All that's happening in the dreams is in metaphorical form mostly. According to one of the books, that I have about decoding dreams, for this particular dream is said this:

"If you dream that your teeth shake or fall, it means bad news, failure, sickness and even the death of a close relative."

In my case I really had a problem with tooth (the same one from the dream), but luckily the dentist saved it...