All dentists receive basic training in root canal treatment in dental school. Although some general dentists perform root canal procedures, many refer their patients to endodontists. Endodontists have two or three years of specialized training beyond dental school in root canal treatment. Many have performed thousands of procedures and are familiar with all the potential complications that may arise. They have specialized training in the latest technology, including the use of the ultrasonic, apex locator, digital imaging, and the operating microscope. Endodontics is one of the nine specialties recognized by the American Dental Association. Because they limit their practice to endodontics, endodontists have lots of experience in handling difficult cases, such as teeth with narrow or blocked canals or unusual anatomy.