Q. Hi – i had a route canal done in the uk about 4 years ago on one of my back tooth, i think it may have been slightly complicated as i had 4 canals of which 3 where treated but they didn’t want to go further into the nerve than was necessary (from what i can remember). My tooth has recently started to get sensitive and in the last couple of days it has started to go grey/black. From the info that i have given (which isn’t much i appreciate) what do you think my options are? Thanks for your help