My friend is a dentist, and she used to do work in prisons. She said some of the inmates (especially meth users because of the way it makes them crave sugar and dries out their mouth) had so much plaque buildup that the plaque was all that was holding their teeth in. Plaque would cover the roof of their mouth and when she removed it some/most/all the teeth would come with it.
Great post. Had no idea this stuff happens.