Just as in medicine, dentistry has specialists that invest in additional training to develop expertise in specific areas of dentistry. An endodontist is a dentist who has undergone a minimum of two years of extra postgraduate training following dental school. An endodontic practice focuses primarily on root canal treatment, related surgery, and treatment of damaged teeth resulting from accidents and injuries. All dentists are trained in diagnosis and endodontic therapy, however, some teeth can be especially difficult to diagnose and treat. Because of the vast network of nerves in the mouth, the pain of a damaged or diseased tooth often is felt in another tooth and/or in the head, neck, or ear (referred pain). An endodontist specializes in diagnosing and treating this type of pain. An endodonitc specialist performs routine as well as highly complex procedures with an emphasis on retreatments, microsurgical treatment and treatment of the medically complex patient.