Because the root canals are very fine and curved in some teeth it may be difficult to clean the canals completely. Occasionally a piece of a file may separate in the root canal due to strain placed on these fine instruments. Sometimes these are retrievable but they may also be sealed in the root canal as part of the filling.
Pain or discomfort may occur between appointments due to ongoing tenderness of the tissues around the tooth, a flare up of an abscess or hair-line crack in the root.
An abscess or ongoing pain will rarely persist following root canal treatment. If this occurs the tooth will require some further treatment. Occasionally an additional surgical procedure may be required if discomfort persists.