I had a root canal in one of my lower molars some years ago, and recently the gum
around it became inflamed. I went for my normal check-up and the dentist said that it was infected and prescribed antibiotics (I finished the prescribed course). She also told me to brush three times a day. I went back the next week, as the filling fell out of it, and she said that it was looking better, re-filled the tooth and recommended Corsodyl for a couple of weeks.