RESUMEN
Surgical removal of impacted mandibular third molars frequently require tooth sectioning or bone removal. In this study, 361 mesioangular or horizontal impacted mandibular third molars are removed surgically by tooth section, the methods of tooth section are classified as 4 stages and 12 grades in the number of times and technics of crown or roots section and difficulties. Grades and their cases are followings: 1. occlusal crown first section(100, 28%) 2. distal crown first section(69, 19%) 3. occlusal crown second section(29, 8%) 4. distal crown second section(52, 14%) 5. occlusal crown first section and root section(10, 3%) 6. distal crown first section and root section(27, 7%) 7. occlusal crown third section(3, 1%) 8. distal crown third section(22, 6%) 9. occlusal crown second section and root section(13, 3%) 10. distal crown second section and root section(17, 5%) 11. occlusal crown third section and root section(2, 1%) 12. distal crown third section and root section(17, 5%)