A total of 11 2 severely tetr acycline-stained teeth in 20 patients were treated by endodontics and nonthennal internal bleachin g. All teeth were healthy , intact, and had no history of trauma. The patients were monitored for 5 to 15 years. Excellent, permanent esthetic results were obtained with no side effects. The quality of endodontic treatment and lin gual access restoration were important factors in the longevity of the bleaching results