Is it that your teeth just continue to decay and nothing you can do will stop that once it starts? (warning, a slight rant ensues) I recently had a existing cavity from way back (unkown amount of time go bad) and my existing root canal from about 8 years ago go bad, such that I had to have the root canal redone and the cavity filling redone. This is pretty damn annoying! The root canal had become slightly sensitive and the xray showed a bit of infection below the tooth, but how m...