An endodontist is a dentist who specializes in treating diseases of the inside of the tooth (the pulp). One of the most common procedures that endodontists perform is root canal therapy. A root canal procedure is performed when the tooth is severely infected or decayed. It involves removing the pulp chamber of the tooth and filling it with a special material. In treating patients with tooth disease, an endodontist can also educate them on root canal therapy, surgical endodontics and dental implants.