If I could rate lower, I would have. My experience with ProGrace left me traumatized, in pain for years and with one less tooth than I started with. I went in because a crown fell off one of my back, lower molars. They suggested a routine root canal and permanent crown. the dentist botched the root canal, broke through the root end and pushed the material into the area where the nerves are. i have had root canals before and they have been quick and painless. i used to joke that I'd rather ha