When a tooth becomes structurally flawed as a result of decay, a failing filling or fracture, there is often little tooth structure left to work with and a crown is necessary. Filling material alone is not strong enough to replace the missing tooth structure. It will often fail, or worse, the remaining tooth structure can fracture necessitating extraction of the tooth.  A crown replicates proper tooth contours and encapsulates the remaining tooth to strengthen it and restore proper function.