An endodontist goes through several years of education before they are qualified to practice in the field. They go through four years of general dentistry education. They get at least two years of advanced education in endodontics through a post-doctoral program accredited by the American Dental Association. If they want board-certification from the American Board of Endodontics, they have to further fulfill all the necessary requirements before earning diplomate status from the board.
If you need the services of an endodontist, you will usually be referred to one by your family dentist. If you have to choose one yourself, you need to consider several things, including educational qualifications, experience, continuing education, patient relations, and the like.