Having dreams about teeth isn't always a bad omen. I read that when you have those kinds of dreams, positive major changes are coming. I've had many teeth dreams before an event that changed my life for the better, including getting my day job (been at it for 7 months now).

One tooth dream I had happened more than once. I was spitting out shards of glass. In this case, I was able to determine that when someone upsets me, the words I typically use can "rip someones soul apart like shards of shattered glass ripping through your skin". I took it as a warning to watch my mouth and tone it down a bit. I've done that and haven't had a dream like it since.