Dr. Bill Dorfman: Well, let me show you some animation so you can see exactly how this works. Inside the mouth we have a tooth; the tooth has a hard surface and then inside the tooth is a soft area, that's the nerve that's the pink part that you see here. Now what happen in a root canal is bacteria eaten to the tooth and then the tooth becomes infected. And the infection goes right in to the nerve when that nerve becomes infected we need to remove the nerve, otherwise your face just blows up. So it's really important to do a root canal when you start having pain like that.