Q. 15yrs or so ago I had a dead nerve in my upper left 2 ….the dentist at the time recommended a crown. Whist my crown was being made i was fitted with a temporary crown. Recently this crown came loose so I went to my new dentist to have this re-glued. To my horror the tooth inside the crown was rotten and was beginning to rot my front tooth. I had been complaining to the dentist that there was a smell coming from the tooth. The dentist discovered that on what was lef of my tooth was a lot of cotton wool ….which appears to have been left from the temporary tooth back 15yrs ago. What I want to know is what role did this cotton wool have on my tooth decay (there was a lot of cotton wool) ?……or why would my tooth rot like this as I have great oral hygiene?,