Q. Hi Please can you help? I had a root filling done on one of my front teeth 5 years ago….the same tooth has been going black ever since. I have recently changed dentists and have discovered that when the original root filling was done a piece of cotton wool was left inside, so no matter how much i brushed my teeth it wasn’t making a difference to this tooth. This tooth is now causing the tooth next to it to discolour. My dentist has told me that because i get nhs help (full exemption) then there is nothing they can do for me? I think i need a cap or crown on it (don’t know which). The tooth is causing me real self confidence problems and i dont know what else to do. I hope you can help. Many Thanks.